Continuity mistake: When Gus is falling from the building on his skis the sky changes colour from shot to shot.
Continuity mistake: When Superman enters the acid storage room we have a glance at the temperature needle and can see it is way to the right; but the chemist is calm and no alerts are active. Minutes later, before the place explodes, while Superman is freezing the lake, the lights in the room turn red and the chemist freaks out, but the needle is further from the danger zone than it was when we first saw it.
Visible crew/equipment: When the evil Superman flies into the junkyard, you can plainly see the wires from the harness.
Revealing mistake: When Superman gets blown away by the bombs, he is being smashed onto the rocks. You can easily see that the rocks aren't real, but also that when he rises up again, you can see the cardboard rocks dent.