Continuity mistake: After Trish jumps out of the window, the position of her feet and legs, and the planks of woods around her, change between shots. (01:18:15)
Continuity mistake: Trish swings the machete at Jason, and knocks his mask off. In a behind shot she holds the machete with both hands. In the next shot she only holds it with one. (01:21:05)
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)
Continuity mistake: After Tommy slices Jason in the head with the machete, he picks the machete up, and in this shot his shirt is dry. In the next shot when Trish goes over to hug him, his shirt is wet, then dry again. (01:22:00)
Continuity mistake: Trish swings the machete overhanded, but in the next shot she knocks Jason's mask off underhanded. (01:24:25)
Continuity mistake: In part 3, Jason was stabbed in the hand and leg yet there are no wounds or damage to his clothes.
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.
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.