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.
Factual error: When Tina and Jason are in the basement, she sprays gasoline at him. It's clear like water. Considering it's covered in cobwebs, it's been there a long time and would be dark in color, because it gets darker as it ages.
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.
Revealing mistake: When we see the shot of David's head, you can definitely tell it's a prop head.
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.