Revealing mistake: When the phone booths fall they don't have any cables attached underneath, revealing they're props.
Revealing mistake: When Superman fixes the Pisa tower, there's a wire on the left side, most probably the system to move the prop.
Revealing mistake: When Superman is in the cave, the computer is supposed to scan Superman making an instant diagram of him. Problem is that Superman's hands position is different to what the scan "sees".
Revealing mistake: Evil Superman supposedly holds Clark by the back of his shirt, but what we really see is his hand behind the back and not holding anything, or at most a part of a dummy which was superimposed with Christopher Reeve.
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 ★