Continuity mistake: When Trish drops the machete it falls half ways on a carpet. When Tommy picks it up it lays on the floor. (01:21:15)
Revealing mistake: After being hit with the machete, as Jason falls and lands on the ground (with the machete holding his skewered head in the air), it is painfully obvious from the skin texture and unnatural facial movements that his head is a replica prop. (01:25:00)
Continuity mistake: This mistake is for the Deluxe Edition DVD only. In the previous film, Jason is defeated by an axe blow to the head, which pierces through the top of his hockey mask on the left side. In this subsequent sequel, the cut in his mask is still on the left side. However, for the menu of this DVD, the hockey mask is shown as the menu art with the same cut from the axe. However it's on the wrong side of the mask, being on the right side now.
Continuity mistake: When Trish and Tommy get to the house, it's pouring rain. When they get into the house, Trish's hair is completely dry and there's just a small wet spot on her blue shirt.
Other mistake: Rob's articles talk about a murder at a cafe. The murders took place at a small grocery store.
Other mistake: There are two mistakes with the ambulance that arrives on the scene to retrieve Jason's body. First, the letters that are supposed to spell DODGE on the front of the ambulance are missing the first D. Second, where is the reversed sign saying AMBULANCE that all ambulances are supposed to have in case people see it in their rear view mirror?
Character mistake: When Trish's car stops running, Tommy states that its the solenoid that is the issue. A starter solenoid is responsible for sending voltage to the starter when the ignition is engaged. 1st problem: The car would not stumble and stall because of a faulty solenoid. 2nd problem: The starter was already engaging while Trish was hitting the key. So bridging the solenoid was pointless. The only reason to bridge a solenoid is to create a connection from 12 volt to the starter when the internal system is compromised due to wear. But that wasn't the case because when she was trying to start it, the starter was turning the engine. Plus the solenoid has nothing to due with the way an engine will perform (running, misfiring, not running).
Chosen answer: He's not possessed. Dealing with Jason made him go crazy. In part 5, we find out he was in a mental hospital for a while, then gets sent to a home for troubled kids.