Revealing mistake: In the scene where Deborah and Luke are having sex in the tent, the coroner (as Jason) comes from behind her, stabs her, and brings the poker upward slicing her upper torso in half. If you look closely in normal play, or put in slow motion, you can see the body is already cut before the poker comes up.
Revealing mistake: Jessica is in the shower crying, and then she grabs a shirt and pulls it on, never putting on anything else. However after Steven punches Robert, he carries Jessica to his car. As he puts her down on the seat, Jessica's shirt rides up, revealing a flesh-coloured thong.
Revealing mistake: After Vicki has been killed, Jessica mourns by her body. She then proceeds to stroke Vicki's hair and face. Well, Vicki dies with her eyes wide open. However, as Jessica strokes her face, Vicki closes her eyes. Her eyes then remain closed for all the following shots of her.
Revealing mistake: Phil, who is possessed by Jason, puts shaving cream on Josh's moustache. Then, he takes a razor and begins to shave his stubble off, and then his moustache - however, you can quite clearly see that Josh's moustache is not there anyway, and has disappeared between shots.
Revealing mistake: As Agent Marcus runs through the woods, away from Jason, all she wears is a white towel around her body, which is just tucked in and over at the top. However it is very obvious that the towel is clipped together round the waist, in order for it not to fall of, most obvious because she trips, climbs over branches, etc. and the towel is always tightly secured.