When one of the construction workers is doing the "nailgun fight" he runs for cover and steps on a rake that shoots up and hits him in the crotch, in a shot right afterwards the rake is missing.
When a couple are killed, one of them is clearly breathing.
When the "dad" victim is killed and falls onto the grill, the grill moves forward and he can clearly be seen grabbing the fence to stop from falling forward.
When the killer falls off of a mining machine, his leg can be seen at the bottom of the screen, indicating that he had hit a pad.
Crew and equipment reflected in car door near the end of the movie.
In the infamous store scene, the cashier woman looks straight at the camera.