This should be stickied.

Magicka regeneration enchantments don't work during combat. So I would have to ask, what's the point?

* Generally doing anything (killing NPC's, clearing dungeons, finding items) that are required for a quest, BEFORE you ever see/receive that quest, breaks the quest. Quests all need to re-check for triggers having already been achieved the moment you accept them. This is a shame, as it goes against the very spirit of TES games, which is to explore freely - instead, exploring freely is currently dangerous as it can break many things.

A lot of games will usually have a "known buglist" thread somewhere - this does a few things, including letting players know that the bug has been acknowledged by the company (and so the chances of a fix are more hopeful), and saves people creating new threads on issues already known. Here's all the issues I've spotted so far, if you have an issue not on the list and want it adding here, please reply to this thread giving as much detail as you can. My hope is this may encourage Bethesda to maintain their own official "known bugs" thread. I'm not by any means claiming this is a "complete list" - but at the moment this seems to be the most comprehensive list in one location on the forums?

Graphics, Textures, Animations etc.
* There is a huge and disproportionate FPS hit upon entering towns for many users (may be related to/affected by items below).
* Light-sources (eg candles, fireplaces) seem to cause a disproportionate slowdown/FPS hit even on extremely high-end systems, just for 1 or 2 lightsources.
* Shadows are extremely low-resolution and pixellated to a ridiculous degree (many people seem to think shadow-rendering is done by the CPU instead of the GPU, which could explain the above, other claims this is not the case - there is some strange CPU bottlenecking on powerful machines though?).
* A combination of more than a few NPC's close together, and light-sources, causes crazy FPS hits (this is really the combined effect of the above three items?).
* FOV seems to randomly drop, sometimes to extremely low levels for a PC user, with no option to change the FOV in game settings, and the .ini changes not always working (using the in-game console should not be forced as this disables achievements). Add a (permanent) FOV setting to advanced options (FOV is an important setting for PC users, as it varies widely based on resolution, monitor size, and distance from monitor as to what a user should be playing with), and ensure it doesn't keep resetting or lowering to console-levels from zone loads.
* Mouse Y-Axis sensitivity appears locked to FPS/performance - this can cause the mouse to require you to use the entire height of your mouse-mat just to look up by a couple of inches at times.
* Quad core CPU's don't appear to be being utilised (despite the recommended system specs requesting a quad-core CPU?).
* .Exe is not flagged as large-memory-address aware (so despite recommended system specs suggesting high RAM, the client will never use that much RAM - users can patch this themselves with 3rd party software in seconds, why can't it be official?).
* Some GPU's seem to be being incredibly under-used, despite apparent lag/FPS drops/slowdown issues - is this related to graphics-tasks being offloaded to the CPU because this is beneficial on consoles?
* Sometimes when walking around, ground textures do not load in quickly enough, and you can be stood on a crazily blurred out, almost single-colour texture for a while (anything up to a minute), before the higher-resolution ground textures load in over them.
* Many heavily used textures seem to be extremely low-resolution (this may not be a bug, it may be that no high-res textures ever existed, or that low-res textures are loading in without the higher-res ones loading correctly).
* Anti-aliasing at certain settings causes a strange blue-line glow/outline around your character and any items you are holding.
* Character animations for sprinting while dual-wielding spells or weapons looks ridiculous and broken.
* Bloom levels in the snow can go too high - causing snow to almost blind the player even when there's not much snow (intentional? Emulating real-life "snowblind"? ).
* The system that auto adjusts brightness (dims/brightens lights as you look and move around) - any chance of a way to disable this? It seems hyperactive on some systems.
* No HDR options available (need a way to turn off HDR altogether, many players dislike it and can have problems with it).
* The small arrows for tracked quests that appear on-screen over doors/NPC's etc. sometimes fail to show at all - unchecking and rechecking all tracked items in the journal sometimes fixes this.
* Sheathing animations for dual-wielded weapons, in third person, appear broken/missing.
* Number of issues with LOD ("Z-Fighting") with mountain snow - flickering can be observed at certain distances, but not others. Most noticable with mountains west of Whiterun, the mountain snow flickers constantly from the Z-Fighting.
* Certain sets of armour on certain genders/races have clipping issues, as do certain helmets with certain hairstyles, badly jarring when playing in third person (try a heavy male character in Orcish armour for example).
* Water doesn't always load in - sometimes lakes can look like they have been completely drained, and you can walk to the bottom of them and still see clear-as-day from one side to the other.
* Sometimes the "fog filters" underwater don't load in (even though the surface of the water was visible, unlike the above bug), and it can seem like you are "swimming" around in thin air.
* Possibly cause by a conflict with a certain batch of ATI graphics drivers, but there is a "black screen of doom" bug that crops up after various minutes/hours of play for many users (see http://www.gamesas.com/index.php?/topic/1263776-computer-black-screening/)
* The "sky-dome" appears to have bad seams - concentric lines are visible in the sky all the way up to the top of the sky-dome, and they move as the lightness level of the sky changes. They are most visible on clear starry nights, particularly as the sun is beginning to rise, where they move across the sky very quickly. (http://cloud.steampowered.com/ugc/650997586435170684/3BEB85EF13638E5B5091016E41B19E8CC5D6A6E0/,http://cloud.steampowered.com/ugc/650997586435172024/6FABBD177FDAEFD46420B71996C281DF4FF6F363/)
* Nirnroot glow effects sometimes lose their alpha transparency masks, causing their glow effects to look like huge solid white textures in a large area around them.
* Many swimming animations are missing from NPC's/monsters, yet they will still enter the water quite freely, looking extremely out of place.
* When riding, the horse often disappears when the camera is getting close due to nearby obstacles - it seems to disappear "too easily" - rather than only disappearing when it should actually be "off-camera" from the camera movements.
* Spider-webs (the ones you can break with magic/a weapon) and flame effects (eg from dragon breath), are sometimes completely invisible and never show up.
* No footprint graphics whatsoever when walking over snow - can't be intentional?

Core Engine/Physics Engine
* Many random crashes-to-desktop - these cause no error messages, it just throws you instantly back to desktop with no notice. There may be many causes of these, some listed elsewhere here, but the outcome is the same.
* Mammoths occasionally shoot 100 feet into the air, and then drop down dead - possibly when two mammoths are following too closely, the one at the back is launching the one in-front of it into the air when they try turning?
* Dragon bones can be seen dropping from a huge height and landing again when you re-approach an area they were left in (and sometimes they'll appear at fast-travel locations when you zone-load in, NOT where they were killed).
* Sometimes simple acts such as opening a door will launch all objects off of nearby shelves/tables etc. that were within a certain distance of the door - seems to be related to how fast your FPS is?
* Objects can get stuck in other objects and will constantly be trying to "jump out of the object" (sounds like two objects banging together over and over without stopping).
* Running over objects/random clutter on the floor can launch them like a cannon has fired them - you can actually injure and even kill your own character with this at times.
* A strange bug can cause objects to get "stuck" to both the player character and NPC's (eg an NPC chopping logs might start getting log-graphics stuck all over it's hands, a player can get animals stuck to parts of their body).
* The instant anything is off-screen, it seems to forget where it was - try very quickly moving your camera back and forth between two people either side of you, you'll see they keep "jumping" into different positions.
* Sometimes the above feature (where things happen differently when off-camera) actually happen on camera - you can be talking to an NPC and suddenly another NPC will warp in in-front of you, an NPC that was elsewhere in the village/building.
* Giants can launch the player hundreds of feet into the air like a rocketship in a single-hit (20 feet in the air would be fine, but they can hit you higher than the throat of the world mountain).
* V-Sync (or iPresentInterval) seems to have a huge impact on many other things ingame, such as the time-of-day the "next day" happens at, mouse sensitivity, etc. - why/how?
* Sound levels are far too low on certain systems, without any way to increase the volume beyond an extremely low level.
* Horses have ridiculous physics - you can climb up near vertical cliffs on a horse at crazy angles, though horses can sometimes die just from falling off a three foot high stone.
* If you kill a character with any form of knockback effect, you can sometimes "push" their corpse through the gameworld, and cause their corpse to be unretrievable or lootable. Is this down to some "speed" setting of item movement - eg a speed of "10" moves it 10 "measurements" per cycle, without any checks on if they would have encountered a floor after say, 7 "measurements" - so they skip right through the world?
* You can also cause living characters to get stuck in the world if you knock them back close to walls/other objects (eg use relenting force to push an NPC back into a wall, they sometimes go "through" the wall).
* Casting spells such as "Raise Zombie" on a dragon's skeleton causes it to shoot into the sky.
* After alt-tabbing out of the game, you need to tab back into the game twice for it to load. Alt-Tab into the game once, the window is selected but you are still on your desktop... re-tab to another window (eg your browser), then tab to the game a 2nd time, and the game loads.

Interface, UI & Controls
* Selling/buying is bugged - if you hover over an item the NPC is selling, and then scroll down the far-left list onto your own items but DON'T move the mouse to the right (so DON'T hover over an item you actually have) - and then tap E - you gain gold for the item the NPC owns, and you can spam it - as if you are selling the NPC's own item back to them. The same bug may also allow item duplication/crashes using the same technique on containers.
* The bizarre fact that the global map can be scrolled with WASD but not mouse-dragging, while the local map must be scrolled with mouse-dragging but not with WASD.
* The inability to navigate the perk trees with any reliable and logical sense with a mouse & keyboard, and many other UI inconsistencies and issues with M&K and large screens.
* The "tooltips" for multi-level perks should show both the buff you *CURRENTLY* have, and the buff you will get if you put one more level into it. Atm it doesn't, and it's not clear whether the game is showing what you currently have, or what you will have if you put another level into the perk.
* Appears to be no way to sort the inventory - can't sort by items worn, item weights, item values - stuck with pure alphabetical text lists. Not even small icons representing "Item types" next to the items?
* Mouse-clicking in menus is very buggy - sometimes mouse-clicking directly on items in the UI fails altogether. Other times is works for some but not all. Yet more times clicking anywhere but exactly on the text itself causes the menu to close instead of selecting the item your mouse was next to. Using the keyboard seems to be fairly reliable - it seems to be the mouse controls that are very broken in the UI.
* If you use WASD to navigate the UI and hit enter, but your mouse is over something else in the UI (an item, a dialog option, etc.), hitting enter can select the item the mouse was over rather than the one you used keys to navigate to (and the reverse is sometimes true).
* Key remapping doesn't seem complete - many interface related key presses (eg favourites and hotkeys) screw up if you remap those same keys (eg remapping the F key that changes to third person, interferes with the F being used to favourite things, changing the WASD keys to cursor movement doesn't allow you to use cursor keys for lockpicking, etc. etc.).
* Should be far more hotkeys open to PC users for the favourites/quick-list (how about supporting ctrl+key, shift+key, alt+key to expand the list massively?).
* Players should be able to hotkey a combination - eg hotkey a shield&sword combo, or hotkey a dual-wield combo.
* There is no way to quickly check buffs/debuffs - without a painful chore going through the magic menu.
* Key-bindings seem to "break" for hotkeys if you try to switch from "magic in one hand weapon in the other" (and possibly other dual-wield combos seem problematic with the favourites hotkey system?)
* If you middle-mouse-wheel while using the enchanting station, it can zoom your character out instead of just scrolling the on-screen lists - this can cause your character to be permanently stuck after trying to leave the station.
* Appears to be no simple way of seeing if you already know a spell listed in a container/NPC etc. - surely spell tomes for spells you already know could be greyed out (or if items had small thumbnail icons by their names, as they should, the icons could be greyed out).
* The "R" key to unlock dragon shouts, even though you have souls, occasionally doesn't work (may just be from key remapping, but even without remapping the R key, this can still happen, spamming the R key sometimes unlocks a shout).
* Both racial powers, and shouts, default to the "Z" key - making it awkward/confusing to use both racial powers, and shouts, together. (and this isn't explained anywhere)
* Dragon shouts often seem to unequip themselves - you can be tapping Z and nothing happens, and find your dragon shout had unequipped itself.
* The game does not make it clear to the player they have to press "R" to spend dragon souls to unlock dragon shouts - MANY players have gone through the game with lots of dragon souls and locked shouts, never knowing how to unlock the shouts.
* Some conversations cannot be backed out of with tab, and other conversations that shouldn't be able to (eg when guards want to arrest you) CAN simply be tabbed out of. Sometimes the exit conversation button disappears and the conversation cannot be tabbed out of either, so you are stuck in a permanent conversation.
* If you read a book and tab out of it, the entire UI starts playing up - moving the mouse over UI elements causes random elements to be ignored altogether as if they didn't exist - the only fix is to exit the UI completely then re-enter.
* Trying to rotate items in the "zoomed in" view is extremely unintuitive and problematic - it can be extremely difficult trying to rotate items to get them a particular way around.
* Not all dungeons or map waypoints get flagged as "cleared" even after you have cleared them.
* Not all mice have mouse-wheels, but there are some controls that require a mouse-wheel and there appears (?) to be no keybound alternatives, eg map zooming or zooming in on items.
* Media keys (eg volume control keys) do not work ingame (other games don't seem to disable keyboard media keys).
* Seems to be no way to attack with any weapon at all underwater, even though enemies that happen to be underwater can attack the player.
* If you have your fists out in third person, and go into first person, your fists don't appear on-screen but you are unable to interact with anything (eg forges, enchanters) - you need to unsheathe and sheathe some weapons again to clear it.
* Sometimes interface text (on-screen messages) get "stuck" on and never fade - they can be replace by other messages (eg when you cursor over a door) - but revert back to the same message rather than clearing when your cursor moves away from the door.
* Caps-lock functionality frequently gets reversed (can cause problems particularly when trying to chat with people in Steam overlay chat).

NPC's, Companions, Creatures and their AI
* Sometimes some NPC's (not followers) get 'stuck' following you around (particularly with Farkas) - they will persistently try to talk to you over and over, which interrupts you attempting to fight/talk to others/do anything at all.
* If an NPC is in the middle of a random dialog line (the ones they say as you walk past) when you zone into a new location (particularly a player house), the NPC will actually zone into the house with you to finish what they were saying, then try to leave again.
* NPC's frequently do their animations half-way in objects, or many feet away from the objects they are apparently interacting with - eg appear half-way embedded in the floor, or leaning on a post 5 foot away, or animations bugging causing them to spin round-and-around while apparently sleeping on a bed.
* You can place a bot/basket/tub etc. over everybody's head (by dragging it over them), they won't object to this at all - but will no longer be able to see, so you can murder their family or rob them blind of all their possessions without them making a single complaint, they'll just stand their happily with a basket over their head.
* A single giant and mammoth can takedown a dragon with relative ease (should dragons not be the toughest encounters?). Also seen a single ice-troll solo a dragon.
* Dragons often seem to go out of their way to attack any single critter, creature or mob in range before turning their attention to the player (eg killing every mudcrab around while you pelt it with spells and arrows freely). Is this down to level differences between you and the dragon?
* Marriage sometimes fails to work on characters that should be "marryable" - also there is a distinct lack of certain possible partners of certain races-genders, your partner will sometimes disappear altogether after the wedding and never reappear, and the entire marriage systems seems to be about as deep as a single variable.
* Headless horseman ghost sometimes freaks out and flies through the air at crazy speeds - possibly related to the general broken physics of horses?
* "Fugitive" random encounter can approach and open dialog with the player by surprise, while the player is in the middle of combat with others, often resulting in death. (needs an "is in combat" check before the fugitive tries talking to you).
* Horses, particularly stolen ones, have serious problems upon dismounting - dismount a stolen horse and it can shoot hundreds of feet away instantly.
* Random dialog lines from NPC's are frequently spoken by any NPC's while you are in the middle of conversations and at an audio level as loud as the NPC you are talking to - they often drown eachother out and make it confusing to listen to anything being said.
* Talking to a fist-fight opponent immediately after the fight (while they are still kneeling) sometimes causes dialog problems.
* If you ask a companion to leave, it occasionally doesn't flag your character as having "no companion" - and trying to get a new companion (or even the same one that left you) fails, as you are told you already have a companion.
* Companions can sometimes get stuck in certain positions, eg the death/lying down position - but continue to follow you around. So you can have what looks like a snake-person sliding around following you everywhere.
* Companions don't always enter through the same door - eg you can enter a large fort that has two entrances, and your companion will zone in through the back door and aggro half the fort for you.
* Companions (and other NPC's following you) can stand in the doorway of a small room you entered and block you in the room - sometimes you can get the NPC to move if you run around the edges of the room, but not always. You should be able to push your own companions/followers out of the way by running into them.
* Companions sometimes get stuck at certain stages in dungeons, and instead of continuing to follow you, will run back to the start/get stuck in a certain part, as if there are pathing issues (and you'll have to finish the dungeon alone).
* Companions can charge towards any nearby enemies even while you are sneaking and trying to be stealthy.
* Companion gear resets if you ask them to "part company" then ask them to rejoin - eg if you kit Lydia out in full Orcish armour, remove all the steel armour from her, ask her to part ways then to rejoin you - she'll suddenly have all her steel armour again and be wearing it (Orcish armour will still be on her, but you'll have to sort all her equipment out again).
* Companions can often comment on cave discoveries (eg "This might have some treasure in" type lines) when you exit the dungeon, rather than when you first approach it - they were too far from you when you ran towards the entrance and first entered it?
* Companions in a fight will continue attacking guards after you sheathe weapons, making it hard/impossible to yield to guards.
* Companions will continue fighting with an enemy even after you have "Commanded" it (or calmed it etc.).
* Are Companion equipment sets getting "merged" - or do all Companions have Faendal's bow? For example if you hire Faendal as a companion, then let him go - every future companion seems to have and almost exclusively use Faendal's bow too.
* Faendal takes gold for teaching you archery, but if he is your companion you can immediately take that gold back from him - essentially a free 5 archery every single level.
* Barbos (the dog companion) pushes you around while trying to follow you - probably as it's followpoint distance is the same as other humanoid companions (despite the dog being "longer").
* The skeleton that comes to life in the "above ground tomb" near the Sightless Pit (close to Winterhold), spawns an infinite number of "The Doors of Oblivion" books - just loot one, close then re-open the loot window, and another book is there.
* "Bounty Hunter" NPC's that hunt you down if you have a high bounty, the dialog option to pay off your bounty seems broken - they request 0 gold, and don't clear your bounty.
* Quest NPC's that the player must follow (eg the mage guild tour) will frequently interrupt their tour to greet the player - seems to be issues with not constantly being within a specific range of the NPC?
* Some story-based dialogs get stuck permanently on (they are always having the same specific conversation every time you see them), eg Ulfric talking with his housecarl, until you begin certain questlines.
* NPC's/Critters in fights can rarely seemingly "freeze" - not moving or fighting - if the player moves close enough they sometimes unfreeze and continue fighting.
* Smithing/enchanting/alchemy seem to be incredibly overpowered - make it too easy to get weapons and armour with ridiculously overpowered stats and abilities, seriously unbalancing the game.
* Louis Letrush NPC can become duplicated - three copies of him have been seen, all standing close to eachother.

Perks, Skills, Your Character & Your Items
* The heavy armour "weightless armour" perk constantly forgets itself, which causes your character to become overburdened until you flick your inventory on & off again.
* Smithing an iron dagger or hide bracers nets as much smithing exp as a set of Daedric armour - you can just spam single ingot & strap daggers all the way to 100.
* Arrows, ice shards etc. get stuck in your character seemingly forever, despite zone-loads, sleeping etc. - you can have giant ice-shards or arrows sticking out of your head forever.
* Other graphical effects can also get stuck on your character - eg if you get hit with frost or fire spells/effects, sometimes the graphical effect gets permanently stuck to your character even after the DOT/effect has worn off.
* Using a bow & arrow in third person crouched fires arrow from a point behind and below your character, so it can get stuck in objects or the floor depending what angle you fire at, rather than firing from where your bow actually is.
* Wearing a hood and a mask at the same time causes your character's head to turn invisible.
* Wearing Arch Mage Robes and Thalmar Boots causes your character's calves to turn invisible.
* Certain hood/mask combos allow you to wear the equivalent of 2 helmets/2 masks at once (some sort of slotting/slot number issue relating to helmets being considered different to masks on some items but not all?).
* The "Aura whisper" shout seems to give your character unnatural, brightly glowing eyes, with no way to remove them.
* "Quick Reflexes" sometimes gets "stuck" on - slowing time and giving you "super powers" for minutes or even indefinitely.
* If time is slowed when the player kills a dragon (or if slow time was used at all during the fight?), the dragon corpse seems to "break" and doesn't grant the player a dragon soul.
* Some save-games are randomly disappearing - restoring backups can fix this, appears to be some problem in the save-function that crash that function and cause corrupt/no saves?
* Sometimes the game thinks all your save-games are "corrupt" - but, depending on the cause, this can be fixed by starting a *NEW* game, going through the carriage ride, then loading the old game from within a new-game (if this fails, try restoring the auto-backed-up saves first then going through this new game process).
* The knock-down effect of shield-charge sometimes stops working, seemingly at random.
* At times, the player can no longer get rested/well-rested buffs (despite having no diseases, and not being a werewolf or vampire) - is this impacted by changing stone-signs?
* Custom named weapons default to their base name if you get disarmed with them... likewise if you custom name three similar items (same base/same enchants) with completely different unique names, and drop them all - their names get "merged" - the game seems incapable of keeping track of unique item names the moment the item is no longer on your character.
* Total charges/prices of enchanted items are sometimes loss when changing cells/loading new cells (possibly related to the above when you have more than one item of a similar base type but different enchant/charge quantities?).
* Dropping a soul gem you filled onto the floor can empty the soul gem.
* Even after curing yourself of being a werewolf, NPCs will still make comments about you having "hair growing from your ears" - a certain werewolf related flag is not being cleared?
* Other illnesses have the same "stuck on" problem as above - eg NPC's may comment on you looking sickly even after curing a disease.
* The "Matching Set" bonus for Ebony armour-sets is broken.
* Your reticle sometimes displays incorrectly if you, for example, are sneaking, and quickload a save where you are not sneaking - the "character state" is merging/confusing the reticle system.
* Stormcall shout - is it meant to have such a huge area, and hit everything including neutral NPC's, friendly NPC's, companions and even your own horse? It makes the call unusable in many/most situations.
* If you are over-encumbered, you cannot move at all if you are in 3rd person view (but can move slowly in 1st person view).
* You can have infinite magika by removing and then re-equipping an item that has fortify magika - drain all your mana, then use your favourites/quick bar to remove and re-equip the item that had fortify magika, you'll instantly get however much magika that item fortifies you by given to you. (probably works with health and other similar items if you remove and then re-equip them).
* "Blessing of Talos" states that time between shouts is reduce by 0% (zero percent).
* "Ring of Minor Wielding" lists it's active effects twice.
* Changing to "beast form" sometimes gets confused - you visually change, but get no benefits of beast form, and you are automatically equipped with (random?) weapons/spells you have - but are unable to use them properly due to being in beastform.
* It's possible for non-equippable items to get stuck in your inventory and be listed as equipped (known to happen with a garnet) - you can sell it, but it remains listed in your inventory, so you can sell it over and over for unlimited gold etc.
* Studded Imperial Armor has the same armour rating as Imperial Light Armour (should be higher?), and cannot be upgraded (studded armour can, and imperial armour can, but not Studded Imperial Armor).
* "Blade of Woe" can be upgraded (with the necessary Smithing perk) without requiring any materials at all. (possibly true of certain other unique enchanted items too).
* Destruction magic damage doesn't scale well - eg at level 50, your destruction spells can be doing next to nothing, whereas a melee/bow character will find their damage has scaled incredibly.
* Bounties don't always seem to clear even after "paying them off" - seems to be random (random locations/times/situations?) whether paying it off actually clears it.
* You can jump just as high when encumbered, despite not being able to run - surely jump height should be at best half-normal height when encumbered, at worst unable to jump at all?
* Switching between third and 1st person can reset your breath meter, granting you unlimited underwater breathing.
* You can buy houses & horses for free if, after selecting the dialog option to purchase a house, you are quick enough to open a container and place all of your gold in it. There is a delay between being given what you purchased, and the gold actually being taken.

Environment/Furniture/Interactable Items
* The bookshelf is difficult to fill the bottom/middle shelf with books if you fill the top shelf first (and sometimes leaving the house and coming back later causes the bookshelf to appear empty visually, while still containing the books).
* Books often "fall over" when put on the bookshelf, unless you put larger-sized books inbetween the smaller ones.
* Buying all furniture for your Whiterun home breaks the ownership of the "guest bed" - eg Lydia will no longer sleep anywhere.
* Items don't always stay where you last moved them in cells (particularly important for your own house) - they tend to stick to where they were when you first dropped them/they first appeared in the cell - they will revert to this position if you leave then re-enter the cell (rather than remembering the position you last moved them to).
* Some torches on walls, that look identical to any other torch-on-a-wall, are not interactable (cannot be taken or turned off) - eg some/all torches in Pinewatch.
* The small wooden handcarts dotted around, that often have items in the back of them (there is one in the tutorial/intro cave just before the bear), seem to be as light as feathers despite being quite large wooden items - nudging them just slightly can send them flinging off into the distance as if you had just shot them with an RPG.
* Items placed in certain containers/chests of player-bought homes can vanish for good when the furniture gets replaced from house upgrades, with no warning at all.

Terrain/Areas/Locations
* Certain areas seem to have their own CTD issues relating to objects/creatures being spawned half-way into walls and floors or something.
* Bonechill passage will cause a CTD almost guaranteed after moving beyond the first chamber and heading to the 2nd/final chamber - however playing in windowed mode appears to fix this?
* Pelagius Wing of the Blue Palace causes CTD's/game freeze just after walking through the cobwebs (not every time, but fairly common).
* Wolfskull Caves appears to have a large area of missing texture/missing objects (can see through into a "graphical void")
* Ironback Hideout has no bedrolls/anything under the tents (it clearly should have - there are no beds anywhere for the NPCs to use, every other similar location has).
* Walking around certain parts of Morthal can cause your character to warp and become stuck above the hall of the vigilant, with no way to continue except to reload a previous save.
* The elevator door out of Alfland can break (no longer possible to open/interact with) after leaving the dungeon (need to fast travel to exit, and can no longer re-enter?).

Quests
* There are many items flagged as quest-items that remain flagged even after completing the Quest, and some weigh lots (eg 20lb for a main questline item), and can never be removed dropped or sold, causing a permanent loss to your total carry capacity.
* Quest-items sometimes become invisible in any and all item lists (containers, your own character etc.) - they simply will not show in any lists, which can break many quests where you have to loot a specific quest item etc.
* Sometimes the main-questline when your character first talks to the monks and is meant to extend unrelenting force abilities, the monks actually do not transfer any ability to you at all and the questline is stuck from that point - a reload and trying again can sometimes randomly fix this (seems linked to the function that lets you absorb shouts and souls from dragons/dragon walls - this sometimes doesn't trigger elsewhere in the game, but particularly on this quest from the monks).
* "Unbound" tutorial quest - you can quickly & easily level up many skills by attacking Hadvar / Ralof at the point they tell you to sneak-attack the bear. They will not react and you can attack them indefinitely.
* "A Cornered Rat" - When the NPC "lets you in to talk" - he sometimes doesn't actually let the player in, just closes his hatch and nothing else happens - the quest is permanently stuck then.
* "Loud and Clear" - you can finish this quest but not be given and have no opportunity to receive any followup quests at all.
* "Blood On The Ice" - the graveyard scene sometimes fails to load, causing the quest to get stuck.
* "Blood On The Ice" - if you have the court mage arrested, the quest simple ends prematurely - you are stuck with the amulet, Corlixto's Treasure shop is permanently closed, it feels like a major part of scripting is missing/broken.
* "Gauldur Amulet" - starting this questline/being at a certain stage on this questline can cause a CTD every time you attempt to enter Whiterun, making Whiterun inaccessible.
* "Forsworn Conspiracy" - quest can break if you pickpocket the note during the escape - the quest then updates telling you to check the body, but as you already have the note, you cannot trigger the quest to continue.
* "Markarth Conspiracy"/"The Forsworn Conspiracy" - the guards that arrest you never leave the shrine - you can be arrested, sent to the mines, complete that stage of the quest - but re-enter the shrine and the guards are still there and the whole process repeats, over and over.
* Winterhold College Quest sometimes breaks when you should be starting "Containment" - the necessary triggers simply fail to activate.
* "Blessings of Nature" - the old tree will remain in place with the new sapling growing inside.
* "Battle for Fort Hraggstad" doesn't always allow you to continue to "Battle for Solitude" - it just ends the questline with no way to continue the quests.
* "Season Unending" making a truce can get stuck - Ulfric won't talk to you - possibly he is getting stuck stuck with the joining the stormcloaks quest instead (even if you don't intent to ever join the stormcloaks).
* "Brelyna's Practice" - when Brelyna asks to practise on you, the quest can get stuck at the point where you are supposed to wait for the effect to wear off (no effect listed in active effects, no amount of waiting/zone loading moves the quest forward).
* "Under Saarthal" - casting a fire based spell at the wall can cause a game freeze for some users (frost based spell apparently works fine). Other people have reported that no amount of spellcasting affects the wall at all, other that dual-casting is the only way to fix it.
* "Sentenced to Death" - you can get the dialog for the various "victims" by talking to them, before actually being told by Muiri who the victims are.
* "Purity of Revenge" quest cannot ever be started, if you were on the "Helm of Winterhold" at the time that you should have received the Purity quest (relating to the boss NPC already being killed?).
* "Speaking With Silence" - after meeting Mercer at the catacombs entrance, sometimes the quest gets stuck - you cannot enter without a key, and Mercer does nothing but stand there.
* "Collect bounty from Skald" for Dawnstar bounty quest doesn't seem to update/clear.
* "The Legend of Red Eagle" seems to be (unintentionally) repeatable, if you read the book again after completing.
* "Repairing the Phial" doesn't update after collecting a Briar Heart (even if you collect one AFTER receiving the quest).
* "Battle for Whiterun" - sometimes it's impossible to accept the Jarl's surrender, the dialog simply loops indefinitely, with Vingar Grey Mane standing at the door unmoving - fast travelling at this point fails the quest.
* "Animal Extermination" style quests from the Companions, don't auto-unlock the houses the player is supposed to be entering to complete them, so the player is forced to be a criminal unless they attend the house at certain unspecified times.
* After the companions funeral, the game sometimes gets stuck - everybody remains in a state of mourning, no further quests are received, and any NPC at the funeral cannot be interacted with properly any more (eg Warmaiden shopkeeper).
* Karliah can be asked about the Agents of Stealth, Sabotage, and Strife before entering the twilight sepulcher.
* Performing the optional stage during Muiri's Brotherhood quest BEFORE killing the primary target causes the compass quest marker to vanish.
* "Return to the Jarl of Riften" doesn't appear to progress - questline just gets stuck at that point.
* Sapphire sometimes gets stuck on the bridge by the Bee and Barb, and will not respond to anything or take part in any necessary final Thieve's guild questline ceremonies, and cannot be talked to about Shadr's debt for "Under New Management".
* Heavily scripted events struggle when the player doesn't "do as expected" - eg the very first intro escaping quest, if the player runs up to Alduin and jumps around, Alduin and all other NPC's will just stand around doing nothing, until the player walks to the next trigger point. Or if you run too fast in the intro dungeon, Ralof will stop and stand still rather than run to keep up with you - you have to run BACK to him before he continues on - you have to stay within a set radius for him to keep going.
* Faralda's entrance test quest for the Mage's guild sometimes gets stuck - the player is unable to cast a spell or continue past that point after buying a spell from Faralda.
* Sometimes after defeating Alduin, Alduin simply respawns, over and over.
* Various "becoming the thane" quests remain in the quest log even after becoming thane/completing all quests in an area.
* A number of bounty quests don't seem to spawn the bandit leaders correctly or at all (sometimes only the leader with no helpers, other times only the helpers with no leader).
* Mirabelle's Tour can be interrupted by a random encounter (eg a dragon) - and if Mirabelle is interrupted mid-tour, she will never complete the tour.
* The Bard's Quest can become stuck if you have already picked any of the needed instruments up before receiving the quest (game does not acknowledge that you already have the items).
* Disrupt the Skooma operation quest breaks if you have already cleared that dungeon before receiving the quest.
* An unknown quest in Winterhold, regarding an NPC girl "Isabelle Ronaila", does not get listed anywhere in the journal, making it hard/impossible to complete the quest.
* Completing quest-lines for Companions, Thieves Guild, other major areas etc. appears to have no benefits - re-entering the Thieves Guild, Companion Halls etc. you still get passing comments as if you have just been dragged up from the gutters and are a nobody - is this because of further quests not appearing, variables not being flagged, or is there simply no dialog lines/scripted events to occur once you have achieved "great deeds" for these guilds?
* The "fortify" buffs you get on a particular mage guild quest can sometimes get stuck on your character, giving you the equivalent of permanent, infinite magika.
* Generally doing anything (killing NPC's, clearing dungeons, finding items) that are required for a quest, BEFORE you ever see/receive that quest, breaks the quest. Quests all need to re-check for triggers having already been achieved the moment you accept them. This is a shame, as it goes against the very spirit of TES games, which is to explore freely - instead, exploring freely is currently dangerous as it can break many things.