Revealing mistake: When the killer is getting kicked into the glass cabinet you can see a string pulling the glass so it will break. (01:14:25)
Continuity mistake: When Ray tells Brenda to put on his football gear, he hands Brenda his shoulder pads. When Brenda accepts these she has two braids hanging down in front of her. The camera cuts to Ray for a second then back to Brenda. When the camera has cut back the two braids have moved over her shoulder. She couldn't have moved them with her hands as she is holding Ray's shoulder pads with both hands. (00:49:30)
Continuity mistake: The living-room in Cindy's house has wood plank flooring, which is perpendicular to the plank flooring in the hallway, as seen at the doorway when she runs down the stairs and locks the front door. However, when she runs up the stairs as the killer chases her, the living-room wood flooring at that doorway is gone.
Deliberate mistake: When Cindy is talking to the killer on the phone, and he says, "I could be anywhere. I'm like the wind, baby," she walks into the living-room. Notice the wall behind the couch, it is completely different a moment later. When the killer hides behind the curtains, the wall behind the couch has large bay windows with seating underneath. Then when the killer is at her house the second time, all the windows are gone during the Matrix send-up, so Cindy can run along that wall.
Continuity mistake: When Ray is with Brenda in bed, and she get out, we can see her pillow in one form, and in the next scene is in another form. (00:49:20)
Audio problem: When Brenda is in the movie theater, people are hurting her and yelling at her, but no one's mouth moves. (00:56:30)
Continuity mistake: In the scene where Cindy was fighting the killer Matrix style, she threw a brass ornament at the killer like a Frisbee and the killer dodged it, and the brass ornament should have gone out of the window by smashing through it. But the window was broken by the killer flying out of the window after Cindy kicked him/her. The brass ornament has mysteriously disappeared into thin air. (01:11:40)
Continuity mistake: After they dump the body in the water, Greg tries to get Cindy to agree to the pact. When she doesn't he starts strangling her. When he lets go, Cindy starts to reach her hands to her neck but in the very next shot her hands are at her sides. (00:19:35)