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. (01:25:00)jbrbbt
Continuity mistake: When Fletch and Stanwyk first meet and Stanwyk asks Fletch to come to his home and hear his proposal, Stanwyk is wearing a suit/tie on top but is wearing jeans on the bottom. In the next wide shot as they leave the beach, and again in the next scene as they arrive at Stanwyk's house, he is wearing suit pants. (00:04:50)
Revealing mistake: There are several instances where you can see that the bandages used to wrap up the girls are pre-assembled. When the first girl is "waxed" you can see there are no joins between the bandages, they are all in one piece - almost like a body stocking. You can also see this later with Elizabeth, and it becomes more significant because you see the bandages being wrapped around her head as normal, and then when Watson pulls them off, they come away in one piece like a balaclava, which of course shouldn't happen.David Mercier
Other mistake: It is stated at the beginning of the film that the events that take place start in the spring of 1976, and span over the summer. The Climax, and final scene of the movie, take place on Halloween night. In the scene directly after Milt Sturmfuller was killed, the gas station attendant is seen reading about the slaying in the local newspaper. The date on the paper is Friday September 8, 1980.