Revealing mistake: When Randy, Gale, Dewey and Joel are sitting on a bench in the school grounds, Gale is smoking; but no smoke comes out of her mouth when she takes a drag, nor does the cigarette have any smoke coming off it. (00:58:35)
Revealing mistake: In the opening scene when Phil gets stabbed in the head, watch carefully and you can see the retractable blade popping back out when he pulls his head away. (00:08:05)
Revealing mistake: When the killer attacks Sid's bodyguards, the younger one has blood on his throat before the killer slashes it.
Revealing mistake: When Cici is stabbed in the sorority house, her shirt is bloody, but there is not a hole in the material. (00:33:20)
Revealing mistake: Right before the cop is stabbed at the redlight, you can see blood already on his neck.
Revealing mistake: Towards the beginning, when Gale Weathers is talking to the sheriff who is standing at a podium, you see Mickey filming her with a hand-held camera. A panning shot going right following Mickey with some friends walking sideways reveals him looking at the camera twice. This is because he was waiting for his cue to stop.
Revealing mistake: At the start when Phil Stephens is being stabbed, when the killer draws back the knife you can see there is already blood on the knife. Its only there for a second so you have to look carefully. (00:07:45)