Factual error: In the scene where Kevin is floating, eating a banana just before he is converted in a monster, the water begins to spin in a clockwise direction, but Kevin spins in the opposite direction. He should spin in the same direction as the water. (01:02:45)
Factual error: Superman begins shooting his super intense heat vision at the soldiers attacking him and the other heroes. His vision cuts boats in half, and incinerates the soldiers into ash in an instant. The lasers from his eyes are super strength, with him not yet knowing how to hold any of it back or shut it off, and it is going through the soldiers and boats. Yet the vision leaves no damage at all to the ground the soldiers were standing on, nor does it create any steam when going across the water cutting boats in half. (00:52:15)
Factual error: The rifles that the settlers are seen using are percussion cap rifles. These rifles weren't manufactured until after 1807.
Factual error: When Braniac's robot probe enters the atmosphere over Arizona, fighter jets attempt to shoot it down by hitting it with missiles. The pod is still going fast enough to be on fire from reentry. A missile could not have caught up to an object going that fast. (00:11:30)
Factual error: Dewey corners the gang in the wrecked Mystery Machine and pulls out his duster, which a blade pops out of. There is no way that blade could have fit in the duster. The blade is much thicker than the handle of the duster, and it is longer than the handle and the feathers combined. (01:04:55)