Revealing mistake: The dead woman who is found at the beginning of the movie takes a rather deep breath at the end of the shot. (00:02:40)
Revealing mistake: During the Eddie and Nick fight scene, you can clearly see the stuntman for Eddie. He looks nothing like him.
Revealing mistake: At the end when Mr Norris starts to run through the hallways looking for the punks, he is ambushed and beaten up. If you look closely at his shirt, you can see a small pad underneath on his left, the exact spot where they keep punching him.
Revealing mistake: When Alison discovers Nancy and Tom are dead you see Tom's dead face change in each closeup. When she rushes out of the door in a panic Tom's eyes move as she opens the door and then moves again as the door closes. (01:03:40)
Revealing mistake: Throughout the movie, practically every victim ends up with a broken, twisted neck. The "special effect" used for those deaths is...the actors wear their jackets backwards. It is made even more evident by the plot twist at the end.