Plot hole: When the cop shows Pam the newspaper clippings they include what look to be fresh photos of the real Jason from the events of Part IV, yet no photographer is ever seen taking pictures of Jason alive in the previous films and most likely wouldn't live long enough to publish the photo.
Plot hole: At the end when Tommy is in the hospital, he gets out of bed and goes over to the drawer where his belongings are. He opens the drawer and there's the mask the killer was wearing. How did it get there? The police should have taken that as evidence. There is no way that police would let Tommy keep this mask for a souvenir.
Plot hole: After Roy is knocked out of the barn doors, Pam and Reggie slowly walk over to look, but then Roy jumps up and grabs onto the barn floor. However when we see a wideshot of him dangling, you can see there are no ledges for him to have gripped onto while he fell, and that it's just a flat wall. Therefore he couldn't have popped up because there weren't any ledges for him to have grabbed a hold of on the wall. He should have instantly fallen on the tractor harrows.