Revealing mistake: In one shot when the boat is pulling away from the waterfall, you can clearly see that the shot is the same one they used earlier in the movie. The water from the waterfall now is going up the cliff! They have just put it in reverse.
Revealing mistake: In the scene when the main character is in the library on the internet, she goes to a couple of websites. When the shot shows the URL up top, it is C:\windows98\mydocuments\etc.html. Instead of actually searching on the web they used a premade html page and accessed it from their computer.
Revealing mistake: When the kids are burying Gus, his supposedly dead face flinches when they shovel dirt on him.
Revealing mistake: When the team descends to the bottom of a hole and one female member is first wounded and then dies. After checking her pulse, the others pronounce her dead and begin moving out. As the last one is leaving, the "dead" actress lifts her head up off the ground and looks left. (01:13:10)
Revealing mistake: When Loomis shoots the marshal's window out, when he makes a u-turn you can see the tire marks on the road and dirt from previous takes.
Revealing mistake: Throughout the film, the base station radio is not connected to an antenna. In many lengthy shots of the back of the radio we can see the power cord trailing out the back of the unit, but there is nothing plugged in to the antenna socket. This is especially annoying because base station radio problems are a key plot point.
Revealing mistake: When the guys are driving down the road, you can see Michael isn't under the truck. Yet 2 minutes later, he climbs in the bed. (01:16:25 - 01:18:10)
Revealing mistake: When Henry's mom is pushed off the cliff her cable is visible.
Revealing mistake: In the fight scene at the pier, after Freddy and Jason get thrown into the air by the carriage that smacks into them, they land on the pier in sort of slow motion. Watch Jason's left knee as he lands, you can see a kneepad.
Revealing mistake: When the demon breaks into the jail and the cop is standing behind him. When the camera turns back on to the demon, if you look close you can see the zipper in the left hand side of the demon's suit. (01:08:45)
Revealing mistake: When the man pushes Leroy's body down the basement stairs, as his body is sliding down, when it's almost to the bottom, you can plainly see Leroy lift his head up as he's sliding, although he's dead.