Revealing mistake: In the part in the motel where THING is doing morse code on the table to Gomez you can see the cut-out in the table where the guy's hand is sticking through the table.
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: When Rufio brings the sword down on the rope holding the slingshot, you can hear the intended sound effect, but the rope is not cut. (01:05:20)
Revealing mistake: When Elizabeths car is stolen, Elizabeth puts the phone down and runs across the street. The camera then pans into the phonebox, and reflected in the grey shiny surface of the phone is someone in a white shirt. (00:06:00)
Revealing mistake: At the beginning, when all the guys are running away from the explosions in the war, you see a guy getting thrown into the air, but the black kickplate that propels him into the air is clearly visible.
Revealing mistake: When the king's youngest daughter mounts the Polar Bear King the lack of effort reveals that she does this with the help of a cunningly placed stepladder. (00:25:35)
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 Bill and Ted, are playing Battleship, with Death, you can see at the bottom of Death's neck where the crease is of the cap that is covering the actors head to make it look bald.