Continuity mistake: Robin's position changes when she is thrown out of the window.
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?
Continuity mistake: When Amanda Shepard's watching the video of Dr. Crews forcing Tina to move the matchbook, on the left side of the screen, there are two plaques on the wall two inches apart from each other, but in the next shot as Dr. Crews enters the room, the plaques are now four inches apart.
Continuity mistake: When Jane is killed, blood comes out of her mouth. Yet there is no blood when Michael sees her pinned to the tree.
Continuity mistake: The ax cut is gone when the fireman picks up Jason's mask.
Continuity mistake: The video monitor and VCR on Dr. Crews' desk disappear as Tina looks at the picture of her father. Additionally, there is a model train on the desk in some scenes, but not in others.