Revealing mistake: When Louis gives Gage the lethal injection, because the syringe is transparent you can actually see the prop needle retract in and out of the syringe as he supposedly injects Gage.
Revealing mistake: When Spitz is stabbed with the pitchfork, you can see the line where the fake chest is. It's a different color.
Revealing mistake: In the scene in which Jason kills the captain of the boat, it is quite obvious that Jason uses the blunt side of the machete to slit the captain's throat. (00:39:10)
Revealing mistake: In one shot when Alice is in the shower, as she turns for the soap you can tell she is wearing brown underwear. (00:03:30)
Revealing mistake: When Dana is walking down one hall with Leroy and a bottle of champagne, the exit sign is reversed. (00:53:05)
Revealing mistake: At the end of the movie when they reach the surface, you can see that the horizon is nothing but a big wall with the sky painted on it. You can see the water splashing up against the wall.
Revealing mistake: After Art and Ray successfully blow up the Klopek's house, Ray emerges from the ruins and the porch collapses behind him. It can be seen that the porch supports are dragged backwards towards the house to allow the porch to collapse behind Ray.
Revealing mistake: When Beth is helping Martin out of Bartok's cocoon, you can see Martin wearing pants inside the cocoon. Surely he should be naked. (01:35:15)
Revealing mistake: When little Melvin gets turned back into Toxie, Toxie charges towards the devil and picks him up, and starts swinging him up in the air. While he's doing that, you can tell the devil has been replaced by a very unconvincing dummy.
Revealing mistake: In the scene at the graveyard, after the Warlock assembles the Grand Grimoire and commands it to say God's true name, the fake headstone behind him starts to fall over. (01:33:02)
Suggested correction: Other headstones can be seen falling before this scene.
Revealing mistake: When Angela is pulling the girl up the flag pole you can see that the cable under her hands is being pulled off screen by something else to assist the actress.
Revealing mistake: Obvious stuntman in a flame resistant suit when Eric's on fire.