Revealing mistake: It's painfully apparent that the actors are hung on wires pretending to swim while outside the sub.
Revealing mistake: Near the end of the film when a building is collapsing and people are running to escape the falling debris, several women along with James Coburn are running up some stairs; a block of cement falls and hits actress Gina Golan right in the head. Instead of killing her on the spot, the bolder merely bounces off her head and she continues running up the stairs. (01:40:55)
Revealing mistake: Near the beginning, Montag puts on the fireproof clothing to use the flamethrower. It's really footage of him later taking off the same equipment played in reverse.
Revealing mistake: Wires are visible on the Dalek saucer in almost all shots of it flying.