Deliberate mistake: When Adam kills himself and Hector at the end, the explosion sends a lot of water and parts of Hector into the air. But there is no sign of Adam's blood, body parts or clothing, despite the fact that the bomb was strapped to him. (01:16:10)
Deliberate mistake: The kid who falls into Niagara Falls spends 28 seconds falling before Superman catches him. Niagara Falls is 51 meters in total height. Considering how fast something falls, the kid should have hit the water long before Superman ever entered the scene. (00:39:30 - 00:40:00)