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: When Jason shoves his fist through Dan in the woods his fist is bloody, but when he kills Dan's girlfriend, the blood is gone. (00:27:00)
Continuity mistake: When Jason swings the girl in sleeping bag against the tree, he grabs the head end, yet the head end is the one that hits the tree. [This is fixed and not a mistake in the uncut editions (theatrical and new release dvd) because the uncut scene has Jason taking six swings with the sleeping bag against the tree, including the head end.] (00:26:50)
Continuity mistake: When Tina battles with Jason, the height of the basement roof drastically differs.
Continuity mistake: When Tina is driving, she swerves to avoid Jason. The trees that she almost hits change between shots. (00:43:15)