On to the bugs:
With game effects set to HDR in the options utility, there is a curious graphical glitch. At random intervals and locations on the screen, white box-like objects will appear for a fraction of a second. The objects are roughly the size of desktop icons, and generally square. I have only noticed this happening in exterior maps, particularly with weather effects such as dust devils. Switching to Bloom eliminates the problem.
Dog Eyes
The dog-type creatures (such as Cheyenne, Sunny Smiles' dog in Goodsprings) have an odd glitch. The eyes can become dislocated, appearing outside of the dog's head. They appear to the right-side of the head, turned 90 degrees (so one is above the other, rather than side-by-side). I have seen a partial fix mod for this, but it does not fully solve the problem. It may be related to the color of the eyes.
Objects falling through terrain
I have noticed several instances of items that have been placed on the 'ground' falling through when physics are activated by interacting with a nearby object. One example is the first aid box east of the Yangtze Memorial, which has a skeleton laying on top of it, with a Knife and a box of .357 ammunition on the ground next to it. When one of these objects is disturbed, such as by picking up the ammo, the remaining objects will fall through the terrain. The knife will drop through and disappear, and the skeleton's legs will fall through the ground, leaving the skeleton appearing to hang from the first aid box. Another example is in the cave entrance to Vault 34. There is a skeleton with a 10mm pistol and two boxes of ammunition nearby. When one object is disturbed, the remaining will fall through the terrain. In this case, however, the objects may reappear as if floating to the surface of water, back up through the terrain.
Already-dead bodies not spawning
I have noted several instances of bodies not appearing when they should. For example, the dead courier outside of the Mojave Express office in Primm. Often, when first entering the area, the blood stain will be present, but the body will not. Leaving and returning later, or entering a building and exiting, sometimes cause the body to appear. Another case is the body of 'Johnny' on the cliff west of Goodsprings Source near the five red rubber balls, table and chair. Sometimes the body is simply not there. I have not noticed any pattern. One more instance is outside of the Repconn Test Facility. When first entering the area, most of the Bright Follower ghoul and nightkin bodies around the exterior area will be missing. They tend to reappear on subsequent visits, or as the associated quest progresses.
Cowboy Repeater Reloading Glitch
There appears to be a glitch with the reloading of the Cowboy Repeater gun. After the reloading animation plays (inserting bullets into the gun and cocking the lever-action when finished), the weapon is unresponsive until the fire button is pressed once, after which it will return to normal. During this issue, the iron sights button does nothing. Also, pressing the fire button for the first time has no effect, aside from apparently ending whatever condition causes the problem. Subsequent use of the fire or iron sights buttons work as normal until reloading occurs again. On a minor note, when the player does not have enough bullets to fully reload the gun's magazine, the reloading animation will continue, though the weapon has no more bullets. (Example: the player has 4 .357 bullets and reloads an empty Cowboy Repeater. The bullets will move from the ammo counter to the magazine counter at the bottom of the screen, until all four have been loaded. The reloading animation will continue, however, appearing to insert three more bullets. The weapon will only have the 4 existing bullets once the animation is finished. A small issue, I know.) UPDATE: This issue appears to apply to all weapons that load one bullet at a time, such as the .357 Magnum Pistol, Brush Gun, and Trail Carbine in addition to the Cowboy Repeater. I have noticed that when these weapons are reloading, pressing the fire button will interrupt the reloading process so that the weapon may be fired before being fully loaded. Perhaps the reloading animation does not register when it is 'finished'?
Companion Casino Weapon Confiscation issue
I have experienced this with both Boone and Veronica. When the companions are using modded weapons (The Weathered 10mm Pistol with silencer and extended mags, and a Sniper Rifle with silencer respectively), these weapons are not returned consistently when leaving the casino. I have not seen any problem with un-modded weapons.
Laser RCW not set to energy damage
While using the GECK, I noticed that of all the energy weapons, the Laser RCW is set to 'None' rather than 'Energy Resistance' as other laser and plasma weapons are. I do not know if this is intentional.
Radio New Vegas incorrect newsflash
At the end of the quest series 'I Fought the Law', if the player chooses to aid the NCR in retaking the prison, the news update will be incorrect. Radio New Vegas will mention that the NCR failed to retake the correctional facility, which remains in prisoner hands. This occurs even if the attack is successful and the NCR occupy the facility.
Phantom bullet-proof glass
The most glaring example of this occurs in the NCRCF, though it is present elsewhere. Transparent areas of world objects stop bullets. The best example is the railing around the edges of the watch towers around the prison. Despite being able to see a prisoner crouched behind the railing, shooting at them will hit an invisible barrier, stopping the bullets. It is a relatively minor issue, I know, however it does stand out as a problem. There is a similar issue with railings in Vault maps. For example, in vault 34. Immediately inside the vault, there is a catwalk above a room with a hole in the floor. Several hostile NPCs are also present in this lower area. If the player sneaks close enough to see a target below, they are unable to attack from a crouched position. The projectile will not pass through the apparently 'open' space between the handrail and the floor. Only by standing is it possible to shoot down into the room below. While these are far from game-breaking issues, it does hurt the game experience a bit.
ED-E has feet?
This has been solved with a simple mod, but I'll mention it anyway. The supposedly floating eyebot follower ED-E can trigger pressure plates and tripwires at ground level. Giving ED-E the Light Step perk fixes this, assuming it is 'broken' in the first place.
People hate ED-E?
Occasionally, non-hostile NPCs will suddenly attack ED-E, without turning hostile to the player. I have noted this in the Vicky and Vance casino in Primm (before the town is liberated), and in vault 3. This does not always occur, and I have not been able to pick up on any pattern. Loading an autosave will occasionally prevent a repeat, and an earlier save almost always does. This may happen with Rex and Lily as well, though I have not confirmed that.
Paranoid Loyal?
At Nellis, when the player initiates the quest to raise the bomber from the lake, there is a strange line in Loyal's dialog. When asking questions about the operation, one option is to ask about a distraction. Loyal's reply is that the Boomers will shell a different area to distract them. There is never any mention of who 'they' are, or why anyone else would be interested in the bomber in the first place. I don't know if it is related, but I performed this quest before entering the New Vegas strip and being asked by the NCR ambassador to secure the Boomers' munitions.
Doctor Usanagi hates charity
When speaking to Doctor Usanagi at the medical clinic, one option is to ask about donating to the Followers of the Apocalypse. The doctor mentions that donations must be in 500 cap increments. If the player attempts to give the donation, the only dialog option is to say that the player does not have enough caps, regardless of how many they actually have. I have seen a mod to fix this, which claimed that the donation script was checking the doctor's inventory for 500 caps instead of the player's.
Old Lady Gibson is an animal lover
I have experienced this several times. When using fast travel to go to the Gibson Scrap Yard near Novac, if there are hostile creatures nearby on arrival (bark scorpions, usually) the player's followers will attack them. This immediately causes Old Lady Gibson and her dogs to become hostile to the player if they are present.
One pot, two pot?
For the minor quest at McCarran to fix the food processor, the player is given a list of parts. The final part on the list is 1 Pot. If the player collects all parts as listed and attempts to repair the food processor, they will receive a notice that they do not have all of the parts. The food processor can only be repaired if the player carries 2 Pots rather than the listed 1, but only 1 pot will be consumed.
What grenade launchers are made of
Apparently the Minigun is present in the repair list for the grenade launcher. (Or is it the grenade rifle? One or the other)
Lucky 38 suite upgrade console is possessed
When using the upgrade terminal in the Lucky 38 Presidential Suite, the on-screen location of objects in the list does not match where the mouse cursor must be to select them. The cursor must be offset to the right and below an object in the right-side list to select it, while having the cursor directly on the item will select an item on the left-side list.
Evolved Centaur metaphysical face-lift?
When a headshot explodes the head of an Evolved Centaur, the 'gore cap' that usually covers the severed neck of decapitated NPCs is not present. The front 'face' of the centaur is gone, leaving a 'hole' in the model, through which the terrain is visible.
One-Way wall
Near the Powder Ganger South Camp, there is a sewer pipe near the truck trailer. The pipe has a metal grating inside. The player can walk through this grating into the pipe. The player cannot, however, turn around and exit the same way. The collision detection appears to be facing the wrong way.
Miraculous Resurrection?
An odd thing happened to me last night. I was walking north up the road from Primm, and as I approached the travel-trailer where Ringo's caravan was ambushed, the Powder Ganger body was alive and standing. After returning it to its original non-living state with my pistol, I checked its inventory, and sure enough, it only had the clothing and nothing else. The game forgot that he was dead?
Submarine Radscorpions
Bark Scorpions and small Radscorpions will often appear 'below' the ground. The amount that they are submerged into the dirt varies, from barely perceptible to invisible with the exception of the tail, which sticks up like a submarine's periscope( for comical effect). A common location to observe this issue is the airfield at the south end of the wasteland, which has many radscorpions. The little ones are almost always submerged. Needless to say, this makes shooting them a bit of a challenge, as bullets are better at colliding with the ground than the scorpions are. Additionally, corpses of submerged bark scorpions will occasionally suffer severe distortion (stretching etc.) when re-entering an area where the corpses are present. It's just creepy.
Cold Shoulder from Primm Slim
There is a slight problem with the minor quest to retrieve Vance's 9mm SMG for Primm Slim. Once the player enters the Wins Hideout and acquires the gun, Primm Slim will no longer talk to the player. Attempting to do so will get the standard greeting, but no dialog window will open. Aside from preventing the player from returning the gun, this will also make it impossible to reprogram Primm Slim to be the new sheriff if the player has not done so already. Whoops?
I will add more later.