Revealing mistake: In several scenes Superman has fillings in his teeth.
Revealing mistake: Near the end of the film when Matthew is trying to destroy the pod "greenhouse," there is a shot where Elizabeth walks through. She is supposed to be naked, but if you look close you can see she is wearing flesh colored underwear. (01:55:30)
Revealing mistake: When Katharine Ross pronounces the child dead in the hospital, she pulls a blanket over the child. The kid moves and flutters his eyes.
Revealing mistake: Sandy Duncan is not married in the film, but Duncan's real wedding ring can be seen on her finger.
Revealing mistake: When the neo-nazis burst into Kohler's apartment, they stab him and he slides down with his back against the wall. While Mengele picks up the phone, you can see the 'dead' Kohler blink in the background.
Revealing mistake: At the beginning, as the flying saucer lands at the stadium, the shadow the ship cast doesn't change size as it gets lower to the ground.
Revealing mistake: At the beginning when the teens break into the waste water plant and start swimming, the boy gets attacked then killed by the unseen piranha, and a large blood pool spills out into the water. The girl is but 3 feet away, but somehow doesn't' see the blood as she calls out his name and scolds him for not responding.
Revealing mistake: As the huge guardian goes to move off and chase Elle and Stella, you can see its shadow cast on the fake backdrop sky.