Continuity mistake: After Gus unscrews the computer, the lights go off and Superman's corner becomes dark. From the opposite angle it's perfectly lit.
Plot hole: Gus could not know that Superman was in Smallville in order to give him the fake Kryptonite.
Continuity mistake: After Clark kills the bad Superman, he has dishevelled hair but after he flies it's now perfectly combed again.
Other mistake: When Superman uses his heat vision against the mirror, the beam should be reflected just like in Superman 2 with Zod.
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 ★