Revealing mistake: When the snake leaps out of the cage, you can see a dodgy looking fake snake attached to a wire spring. (00:12:35)
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. (01:14:40)
Revealing mistake: During the opening sequence involving Harold and the clothesline, there is a foreign object on the lens of the camera - noticeable in the bottom left corner in several shots.
Revealing mistake: Near the end of the movie, as they are about to walk out of the barn thinking everything is over and Jason has been hung on the hook from the loft, if you look between the cracks of the barn door, you can see Jason being lowered right before the doors open.
Revealing mistake: Inside the barn, the webbing that the deer head is covered in is fake, as it 'pulls' like elastic when Shelly moves his along the skull. Real webbing would adhere to his bare skin.