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.
Revealing mistake: When John tries to stop the van while Maggie is driving, because he sees the small girl in the road, as the van screeches around the road, you can see the road is covered in tyremarks from previous takes. (00:20:10)
Revealing mistake: After Whitehurst is blown up by the grenade and Andy gets to him you can see Whitehurst blinking his eyes even though he is dead. (01:10:45)
Revealing mistake: When Toulon's puppet stage is set on fire, the flames in the foreground look rather like they are projected from a regularly set row of blow torches, rather than erratically flickering flames on a wooden floor. (00:25:05)
Revealing mistake: When Ernest's jack flies out from under his truck it breaks the back windshield of the mayor's car. Watch closely and you can see the glass shatter before the jack makes contact with it.
Revealing mistake: When Charlie shoots the critter which flies into the air and explodes, we can see the wire the critter is attached to. (01:07:45)
Revealing mistake: When the killer is putting masks on in front of Maggie, you can see the dead body of Tina hanging behind Maggie. The dead body moves / shakes / breathes many times throughout the scene.
Revealing mistake: When the postman goes upstairs to see Julie with the package, he steps on the broken step and falls down the stairs. As he rolls down, the bulky outline of kneepads under his trousers is visible. (00:17:30)
Revealing mistake: When the devil man (Bruce Payne) comes up from under his couch in his caravan, and pushes the mayor through the ceiling - they make no attempt to hide the fact that it is a dummy and its hands are gripping some special handles.
Revealing mistake: When the younger Bowden sprays lighter fluid into Max Cady's face, and he is on fire, for a few of the shots, Max Cady has no head. (01:51:00 - 01:52:00)
Revealing mistake: Brown grabs the contracts and runs away. He and his trusted henchman spot the alligator; in the shot just before the one where Brown gives the ever useful order "Kill him", the alligator is visible in all its fakery. (01:14:15)
Revealing mistake: When Michael comes running up the stairs yelling for Carolyn and Blade comes flying on to him, you can briefly see the string attached to Blade. (01:11:25)