Other mistake: Right at the part where Crazy Ralph is looking in on Paul and Ginny. Ralph hears a breaking of a stick behind him. You can see Jason put the barbed wire up and over the tree. How is that possible? He would have to whip it around the tree, not over it. (00:30:20)
Other mistake: When Jason sneaks up behind the cop and raises the hammer to whack him, the angle shows it aiming for the cop's neck, but in the continuing shot, he strikes the back of the cop's head. (00:45:35)
Other mistake: The narration in the film's trailer incorrectly states, "On a June night in 1980, Friday the 13th, twelve of her friends were murdered." In reality, only eight people were killed then, including the killer Mrs. Voorhees, whom Alice herself killed in self-defense. Mrs. Voorhees was not Alice's friend.
Other mistake: When Jeff and Sandra sneak off to look at Camp Blood, they come across a dead animal. While they're bent down looking at it and have their backs to the camera, the cop for some reason sneaks up behind them and puts his hand on Jeff's back. The camera angle changes and you see the police car parked just off to the left with its red light flashing. There's no way that Jeff and Sandra would not have seen and heard the police car when they came up on the dead animal - it's almost right in front of them.
Other mistake: There is a lot of bad continuity over how many vehicles there are. First there is Jeff's truck then Ginny shows up in her car. Later Paul says they only have two vehicles when they decide who is going to the bar. Later we see Vickie go to her own car when she's looking for her hair brush, so that's actually three vehicles. But there are at least 15 people at this camp. There would have to be more vehicles somewhere.
Other mistake: When Jenny is hiding in front of the yellow car you can see the top of her head yet Jason doesn't see it.
Other mistake: Vicki enters the darkened cabin and flips a switch on a nearby lamp, to discover the power is out. But as she grumbles and crosses to another table lamp that is unplugged, she plugs it in, and suddenly the whole cabin lights up.
