Audio problem: In the scene where Ben nails the door to the wall to keep the zombies out, the sound of the hammer hitting the nail is inconsistent with the pacing Ben actually hits the nail.
Audio problem: Guy flushes the toilet as he walks through the bathroom. The toilet is actually empty and the sound is an over-dub because there is no resistance on the handle when he pushes it down. Had an old toilet like that actually been full you would see the resistance in the lever as the flapper inside rises. (00:04:45)