Revealing mistake: When Gordy gets killed, it cuts to a brief shot of Jesse. When it cuts back to Gordy's body, his head moves.
Continuity mistake: Lisa's shoes change between white flats and white sneakers at different points during the last few scenes.
Continuity mistake: When Jesse and Lisa first arrive at the boiler room factory, Jesse says to Lisa "How long has it been closed down?" And then Lisa replies. To the left of them you can see a large machine, which Jesse and Lisa are standing well away from. But as the shot changes, they are now standing right beside the machine.
Plot hole: When Freddy takes over Jesse's body at the party, there are several people watching through the patio doors when he confronts Lisa. None of these people ever make a sound, even when they see Lisa have a knife fight with a horribly disfigured man with long knives coming out of his fingers. The other party goers are completely oblivious to Freddy's presence until he comes jumping through the glass doors.
Continuity mistake: At breakfast, when Jesse's sister goes to sit where Jesse is about to sit, Jesse says "No!" to her and she sits back in her chair, still trying to get the plastic claws out of the cereal box. As she tries to get the claws out, she is holding the top of the cereal box with her left hand. Then in the next closeup of her, her hand is down by her side.