Arms clipping and bending in unbelievable ways when a player rag dolls upon death. This has always bugged me in VALVe games, ruining the sadness and disappointment that goes along with watching a Rebel die or being unable to save Zoey from a tank.
Guns clipping through walls in multiplayer from the view of another player (looking at you Call of Duty)
Guns clipping through walls in multiplayer from the view of another player (looking at you Call of Duty)