Character mistake: When Gus is programming his new salary raise he mistypes Overide instead of Override.
Revealing mistake: During the Pisa tower scenes, the sky is always the same, plus the balloons in the stall have the exact same position, revealing not only that the shot is a chroma, but that both scenes were shot the same day.
Continuity mistake: When Superman struggles to stop being dragged by the computer, there is debris all over the floor. When the computer explodes the debris disappears.
Factual error: At the start we see a blind man and his guide dog, who runs off after a smaller dog. Guide dogs are specifically trained not to do this before being given to their owner.
Revealing mistake: As Superman takes off from the coal mine, there are two dark lines over him. That was an attempt to mask out the wires.
Other mistake: As Lorelei is held on the wall, there appears to be a chrome ball attached to the belt she has on to give a reference point, and animation was added to complete the scene.
Revealing mistake: After getting blasted by the big missile, as Superman goes to leave the rock face, the surface flexes, showing it's fake.
Revealing mistake: As Superman takes off from the junkyard, the background can be seen through him.
Continuity mistake: When Superman takes Clark's glasses, he folds one arm of the glasses in. A moment later, that arm is extended, and he folds both arms and crushes them.
Revealing mistake: After throwing Clark into the compacter, Evil Superman flies to the control booth. As he walks through the door, the background can be seen through him.
Continuity mistake: When the toy penguin waddles into the smudge pot, its right wing and head catch fire. When Clark sees it, only a small amount of flame is on top of the head.
Revealing mistake: As Evil Superman quips to Clark about wanting to fly, as he struggles Clark's left shoulder goes a little transparent, showing his image was superimposed over the stunt actor.
Revealing mistake: After Clark defeats Evil Superman, he flies to the Statue of Liberty. The whole landscape is a still image with the ripples and the boats completely static.
Continuity mistake: In the junkyard, when Clark comes out of the container, the hole he produces changes shape depending on the angle.
Continuity mistake: Evil Superman is chasing Clark on a conveyor belt and starts to shout and move swiftly as if he was flying. A frame later, from another angle, he is calmed, walking and repeating all previous movements.
Continuity mistake: When good Clark is on the trash compactor about to be covered in metal parts, he lays on a blue car hood. Depending on the angle the hood is barely rusty or very rusty.
Continuity mistake: When Gus is biting Ross, his hand rests on Gus's cheek, a frame later it rests on his head.
Continuity mistake: When Ross is staying late at work, two women are taking their tennis shoes off. When the angle changes, the woman on the left is walking towards her locker and grabbing her tennis shoes again.
Continuity mistake: Noticeable hand-double during the close-up of Gus unscrewing the fuse: Very dark skin and long fingernails as opposed to Gus's short nails and light-brown coloured hands.
Continuity mistake: Before Vera is transformed into a robot, her face is covered in thin wires. A frame later they're gone.
Answer: There were rumors that Hackman was angry with the Salkind Brothers (the producers) for firing director Richard Donner, though Hackman later disputed saying that. His explanation, though he may have been downplaying the real reason, was that he had a number of other movie projects at the time, and he also did not wish to continually play the same villain in an ongoing movie series.
raywest ★