Continuity mistake: In the first level on the boat, there is a red crate in the center of the boat. If you get on top, you can see inside. You'll just see a room... With nothing. Open the crate and see bodies. They weren't there before.
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.