Continuity mistake: In one scene a security guard gets squashed by a door. It then pans over the door, and you can see large grey marks in the door, from where it's been bashed in by Jason. The dents are quite different from when the camera pans over the door, to the wideshot. (00:56:25)
Plot hole: Right before the second boy gets killed he wakes up after having a dream of Freddy and sees his dad sitting next to him. When the boy taps his dad lightly his head falls off and we then see Jason standing there. In order for this to have happened, Jason would have had to unbutton the dad's shirt, chop his head off, put it back in place, and rebutton his shirt without getting any blood anywhere on the body and without the dad putting up a fight. Also Jason waits until after the boy wakes up and sees his dad dead before killing him. Wouldn't Jason just kill him in his sleep like he does to the girl in the cornfield later on in the movie?
Suggested correction: Maybe Jason set up the dad to freak out Blake. His dad left him on the porch and we don't see Jason actually kill him.
But this is not the way how Jason works - he doesn't play games as Freddy does; the moment he sees the person, he just kills. Killing of Blake and his dad was way off Jason's Modus Operandi.
Continuity mistake: When Will and Lori are driving in the van you see a car's headlights behind them in a close up shot. However, in the previous wide angle shot, there was no car driving behind them. (00:46:25)
Continuity mistake: When Jason throws Freddy to the wall in the burning house, you can see a window on the wall. Now, the distance between the window and the corner of the wall is about five feet. This gives Freddy space enough to hit the wall and not hit the window. However when Jason picks Freddy up you can see the distance has increased to about one feet. It's like they've put in an extra window where there should be a wall instead. (01:14:30)
Revealing mistake: In the scene were Freddy and Jason are fighting at the end, when Freddy puts the machete in Jason you can easily see a rip in the shirt made for the machete to go in.
Continuity mistake: When Freeburg and Shack are handing out the flyer's for the party, we see Kia cross her arms as Gibb ask Lori if she wants to go. When it cuts Kia has her arms down. (00:26:05)
Continuity mistake: When Jason slams his machete in to the panel and gets electrocuted, the panel is pretty damaged. When it cuts to him grabbing onto Stubbs, it shows the panel again, much less damaged. (00:59:10)
Continuity mistake: When the girl goes skinny-dipping you see her leaving her purse and clothes on the pier. When it cuts they have suddenly disappeared. (00:03:00)
Revealing mistake: In the cabin fight scene while Jason is trying to free his machete from the table, Kia picks up a wrench and starts hitting him. When she hits him across the face, you can see the wrench bend in her hand.
Continuity mistake: When the two guys are out in the corn field smoking weed the kid is looking at a glass and a jar while holding them up. In the next shot the glass and jar is lowered and he is looking at the other guy. (00:39:50)
Continuity mistake: When Lori says "Why don't you start in the kitchen and get us some beers" Kia sits next to her with her hand to her mouth eating popcorn. The hand keeps changing from being down and being by her mouth between the shots. (00:10:25)
Continuity mistake: Out at the party when Kia comes to Will and Lori and says, "Let's go shake our ass on the dance floor," you see Linderman standing a few feet away from Will. When it cuts Linderman is suddenly close to Will handing him a beer. (00:35:10)
Continuity mistake: After Freddy and Jason lands on the pier you see Freddy crawling facing forward. When it cuts Freddy is suddenly looking backwards at Jason. (01:20:15)
Audio problem: About fifteen minutes into the movie, when Gibb says, "I am so under the limit, Lori," her lips don't match the line.
Continuity mistake: When the three girls are sitting outside the school, Gibb puts her cigarette to her lips twice.
Continuity mistake: In the end of the movie when Jason comes through the water stabbing Freddy with his own glove, you can see the spikes only coming out of Freddy's chest. When it cuts to Freddy falling to his knees, the whole fist and parts of his armwrist suddenly has gone through his chest. (01:24:00)
Continuity mistake: When the sheriff says, "Or so help me God I will lock you up," to Stubbs, you see the sheriff lift his hand with the cigar up. When it cuts his hand is down. (00:51:00)
Continuity mistake: The end of Jason's machete changes throughout the whole movie. Sometimes it has a rounded end, sometimes it has a pointed end and so on.
Revealing mistake: When Freddy is about to kill Gibb, the claw near the top right that is in the locker bends like rubber.
Character mistake: There was no chance of Will and Lori knowing what's happening with Mark in the house. Neither him nor anyone else called them. So what made them rush home with van, after they've been casually driving in their previous scene?
