Continuity mistake: When Debbie is killed in the hammock, in all shots of her, the quilt covering the hammock net has patterns sown on it, such as flowers. However, in the closeup of Debbie as the knife comes through her chest, the quilt covering the hammock is the same one as before, however you can now see it is suddenly the other side of the quilt.
Plot hole: Jason somehow manages to get the two halves of Andy's dead body on the wooden ceiling rafter, with no blood dripping onto the hammock and staining it, or getting none onto the floor. Debbie then gets into the hammock, and about a minute later, blood starts dripping - for no apparent reason. Why?
Revealing mistake: When the snake leaps out of the cage, you can see a dodgy looking fake snake attached to a wire spring.
Continuity mistake: When Chris and Rick get stuck in the woods, Rick puts a coat on Chris. In a wide shot Chris pulls the sleeves of the coat up and then starts adjusting the shoulders of the coat. It cuts to a closeup and she is now rolling the sleeve up again, and then adjusts the shoulders again too.
Revealing mistake: When Chris is trying to escape out of one of the first floor windows, the shots you see from outside are of a stunt double with really bad frizzy hair.
Continuity mistake: When the camera pans past the window, to the door, showing Chris walking up to the cabin, there is no painting hanging next to the door. When she gets in and talks with Rick, there is a long painting hanging to the right of the door.
Continuity mistake: When they arrive at the lake and get out of the van, the long shot from the passengers' side shows Chris getting out and slamming her door, but then the next shot from the driver's side shows her getting out and slamming the door again.
Revealing mistake: When Debbie is in the shower and we see a shot of her through the shower curtain, you can see she is wearing white underwear.