I walk everywhere at normal speed. Exploring the environment is the primary reason I play this game.

I love all of the little details that have been mentioned by others, but the detail I love the most is the sound of the startled birds taking flight outside of Riverwood.

Nearly 900 hours later and I just noticed lantern candle flames. I forget where it was, but there was a mine or dungeon with a candle lantern on its side, but still burning. The flame was still upright, exactly as it should be.

This just happened.

I'm playing a dunmer who has a very serious case of inferiority complex and a hatred for other races. So I walk into a shop in a little town to the south and the shop keeper greeted me with something like this "I don't know why we let you foreigners wonder our lands". That was enough for me to stab him in the chest and leave the body on the floor.

After wandering the land for a while today I returned to the same town and decided to stop at the same shop. To my surprise there was another guy there and he greeted me with this "Be welcome, unlike my brother I don't have any problems with strangers. Afterall I've met a lot of you during my time in the stormcloaks".

Not only I let him live but I even bought something I didn't even need from his shop just because he was so nice.

The shadows of hawks on the ground as they fly above.
Fish jumping in and out of the water.
Different npc and animal factions fighting each other.
Burn marks on chests after setting off a fire trap.
Different types of traps that can be triggered by the player against the enemy.
Bards playing in taverns and being able to request a song..for a price
Buying a tavern patron a drink.
Giving charity to beggers with the extra never before seen in any Elder Scrolls chapter benefit of a..BLESSING!
The sixy looking statues in the Temple Of Dibella.
The different items left at shrines and places of worship such as jewelry,weapons,shields, food, drink etc.
The many variations of grass near each other in the wilderness.
The labels on liquor bottles.
Books in rented tavern rooms.
Removable torches from dungeon.
The different look of ore types and how they blend in with the environment.
The horrible living conditions of miners in Markath while the rich live in style.
The bone chilling heart freezing muscle paralyzing arctic wind.
The little bunnies.
The friendly doggies.
The psychotic claw snapping raging mudcrabs with their excellent camouflage.
The weighty feel of weapons during combat.
The evil voice of Dragons when..they talk.

I love the way the imperial captains nod their heads to the Headsman so they can start chopping. ^^

Auroras...

Fish gathering beneath dragon flies hovering over the water. Now that I know how to find the right place to cast my line I wish I had a working fishing pole. Although I've heard you can "arrow" the fish.

I like listening to the bandits sing while I sneak up on them.

I love everything mentioned, but what made me cough up my coffee was...When I'm going to enter Breezehome and a guard starts to say something, then I'm inside and the guard is there too, saying: No lolly-gagging!

I always like a little mystery, so my favourite is those runes or whatever they are carved on the bottom of the Insect-in-a-Jar lids. I have no idea what they mean or whether they mean anything at all though.

So many good details listed here. I love the townsfolk pointing at the flying dragon and the fallen torch flames still flowing up (though I haven't seen these myself).

I found a new little detail, probably the smallest in the whole game. Next time you see a Torchbug, get close to it and watch it hover around. When it moves from side to side, its legs and antennae sway with perfect physics. To think, in a world as massive as Skyrim, Bethesda even added physics to the hair-thin legs of Torchbugs.

The skeleton with a stone block tied to his ankle at the bottom of a waterfall. Made me lol.

You know that's just a random/generic line that an NPC will say when you're using a container, right?

They say similar ones while you're picking stuff up. Like... "What are you doing with that!?" "Put that down!" etc...

The bugs are really cool, but I have to say, I really like the Falmer dungeons. How they herd and slaughter Chaurus, which is used to make their Armor and Weapons, and how they cultivate the glowing mushrooms the Dwemer made them reliant on.

*The way some of the followers will speak up and startle the tar outa me. " Hey, look cave....." &" Don't get to far ahead"
* The sound of the wind blowing.
* The fact that the slower I walk around the more I notice and I wonder how much of that the ppl who already "beat the game" got to see.
* The way followers will bob up for air when swimming across large bodies of water. ( first time I saw it I )
* The way that if I want to I can mine ore manually by swinging the pick myself.
* Some of the sarcastic remarks you get if you took that side in the Civil war.
* The way followers don't wait for you, but will attack something hostile on their own.

I love the fact that shooting a beehive will knock it down, and shoot a butterfly will drop two wings.