Corrected entry: The capes of both Supermen ruffle when they are on the moon - it must be windy up there.
Corrected entry: When Superman is on the moon and straightens the American flag and Nuclear-Man comes from behind and knocks Superman and the flag down, the next shot shows both men fighting on the ground with the sun shining behind them. If that is the only source of light in the solar system, where is the light coming from in front of them?
Corrected entry: In the scene when Lex's commission is increased and he decides to take control of the business, when he holds up the bill for nuclear man to burn if you watch carefully you can see that as soon as it catches fire Lex's hand and the bill both disappear.
Corrected entry: Since the super-powered villan is a clone of Superman, shouldn't he look like Superman? Lex Luthor never mentioned using anyone else's DNA to create the super villan. The movie makers could have created another image of Christopher Reeve. It was done in the previous Superman movie when Clark Kent is battling with the bad Superman in the auto junk yard.
Corrected entry: When Superman plants the evil super guy on the far side of the moon in the elevator, the sun eventually shines through to revive him. The problem is that the moon spins on an axis that prevents the dark side from ever seeing the sun. This is why we only ever see a single view of the moon.