Continuity mistake: The water is murky on the surface but underneath its lit up and blue.
Continuity mistake: When Cort starts the RV and drives away, all of the interior lights are on inside the RV. Yet when we see an exterior shot of the RV before it flips over, the lights inside the RV are no longer on. (00:37:10)
Revealing mistake: When Tommy goes to the Sheriff's station to warn everybody about Jason, Sheriff Garris ignores this warning. Tommy freaks out and grabs a shotgun but Sheriff Garris throws him to Deputy Rick, who drops the fast-food boxes he was holding. We can see and hear that these boxes are empty when they go flying. (00:10:40)
Audio problem: In the film Tommy is on a boat in the lake and Jason comes after him. Tommy opens up the gas can and spreads gas in the water around the boat and ignites it. When the gas ignites and the scenes following have the fire giving off a cracking sound (like wood burning), fuel burning on the water would not have that type of sound. (01:14:25)
Continuity mistake: When the group of kids enter the police station, Cort has his headphones around his neck, then a few shots later, he takes them off his ears. (00:05:10)
Continuity mistake: When Cort and Nikki drive away in the camper, there is a large framed picture on the wall behind Cort above 2 smaller pictures. In one exterior shot of the camper pulling out, the larger picture is gone, but it re-appears in the next scene. (00:37:20)
Continuity mistake: In the RV scene, all of the lights are on. After they are killed, its completely dark.
Visible crew/equipment: When one of the female counselors is walking towards the window because she heard a noise you can see the top of the camera shooting the angle from outside above the window sill. (00:44:40)
Continuity mistake: When Megan and Tommy drive up on the roadblock, Officers Pappas and Thornton chase after them. Notice the precipitation on the windshields of the police cars, and Megan's car. Seconds later when Officer Pappas is on the radio with the Sheriff, his windshield is dry, without any rain drops on it at all. (00:49:00)
Revealing mistake: During the Paintball game, Jason decapitates 3 players who are standing side by side all in one swing of his machete, unfortunately all 3 people are of completely different height to each other so there is no way he could have decapitated them all at once. Also, even a viewer with the poorest eye sight can see the boxes the 3 dummies are standing on when their heads fly off. (00:23:15)