Revealing mistake: Zombies: Some of the zombies will flail their arms around to the sides as they move, especially when running. If the zombie walks through a small, single doorway, the arm will pass right through the wall. This is especially noticeable in Nuke Town, where blackened zombie arms pass through white painted walls.
Bug: Zombies - Green Run: A player is hurt slightly by fire, and critically by the lava pools. Players are 'downed' if they stand in the lava for even a couple seconds. But once downed, a player can crawl around all he wants in the lava totally unaffected by it. If you're revived while in lava, you almost instantly are downed again by it.