Continuity mistake: When Michael goes to the bathroom in the woods, Jane is standing next to the road. In the reverse shot, she is standing next to a tree.
Visible crew/equipment: When Jason pushes Dr. Crews down the hill, as he's falling, you can see some kind of equipment attached to the back of his pants. (01:10:45)
Audio problem: When Jason pulls Russell's girlfriend underwater, you can hear her screaming as if she's still above the water. (00:37:50)
Continuity mistake: When Tina throws the plant at Jason it hits him in the chest. The next shot shows it hit him in the head.
Revealing mistake: When Tina kills her father and the dock collapses, one of the logs hits the camera underwater. (00:06:40)
Continuity mistake: Robin's position changes when she is thrown out of the window.
Revealing mistake: Obvious stunt double for Tina as she drops the porch roof on Jason and when Jason grabs her and throws her onto the dock. Her hair becomes a smooth blonde wig.
Continuity mistake: The tent that Judy and her boyfriend are camping in changes size between shots.
Continuity mistake: Jason has on an entirely different outfit in this movie than in part 6. Since he was chained in the lake there would be no reason for his clothes to be different.
Continuity mistake: In the prologue with the narration, you see the scene from six where lightning struck the pole to revive Jason. You also see Jason's tombstone shattering during the lightning strike. In six, you never saw the tombstone breaking.
Continuity mistake: As Tina is speeding away in the car after finding out that Crews wants her committed, she passes by a car that is supposedly the one belonging to Michael and his girlfriend. It is facing in the same direction as she is. If they were coming up to the place for the party, wouldn't their car be facing in the opposite direction, and on the opposite side of the road, which is where we saw it stop earlier in the film?