*minor spoilers*
Did it with oblivion (radiant AI amongst others) and now again with skyrim (again the radiant part of the game). Never has anyone that gotten killed by, let's say a dragon been replaced by a sibling (as far as shopkeepers go) in my game. Also, when I drop a sword or whatnot in a village, not once has anyone brought it to me or fought someone else over it.
Not a big deal, just something I noticed with both games comparing build-up statements to the final game.
Mostly makes me smile, thinking "hey they did it again with me only noticing after more than 100 hours of play"

Oh yeah and the biggest one for me that just leaves me dumbfounded; why do they "lie" about the dunmer voices?! They (beth) seem to know that we ES fans like the Morrowind Dumner voice.
Hence, in both the trailer for oblivion and skyrim you hear the traditional, raspy, cool dunmer voice (the axe-wielding nameless dunmer in the oblivion trailer and arvel the swift in the skyrim trailer)
Then, when the finished game comes out; gone! It just baffles me why they do this. Why not just hire Jeff Baker and let him do the voice again? Or is it too hard with all the spoken dialogue in Skyrim? I suppose not as Jeff did the Ghoul voices in Fallout 3 if I am not mistaken?
Not a big deal but in MW that voice just added so much to the atmosphere of the game IMO. Also find it hilarious that they would just blatantly switch it from trailer to endgame.