Continuity mistake: When Gus takes the tablecloth off, he walks on top of the fallen stuff to talk about Superman, and then the amount of stuff left behind keeps changing between shots.
Continuity mistake: When the bus to Smallville pulls over, the red ambulance passes by twice.
Continuity mistake: After Clark kills bad Superman he rises and the shot changes. His tie knot is now tilted to the right.
Continuity mistake: Amount of snow on the railing changes after Gus flies through with the skis.
Continuity mistake: The two firemen pointing at the lake are standing close to each other. In the wider angle they are much farther away.
Plot hole: During the supercomputer's destruction, the 3 electrical probes that are sending lightning to the overhead pylons to draw electricity from them are no longer flashing. So where is the electricity coming from to sustain the computer's lighting system as the fluorescent tubes are still working?
Continuity mistake: When Vera is getting sucked into the computer, she has white gloves on. Seconds later, during her robot transformation, there is a full screen close up of her hand without any glove. Then, when Vera emerges from the wreckage of the computer a few minutes later, she has her gloves on again.
Revealing mistake: When the firemen's truck runs out of water there's a close-up of the level meter and it reads "Pierreville fire trucks Ltd. Camions a incendie" revealing the scene was shot in Canada.
Continuity mistake: Before the truck is about to fall off the bridge, the blue car in the water moves from a 5 o'clock direction, to a 3 o'clock depending on the shot.
Continuity mistake: While Superman is grabbing the steel chimney, the worker in the far left is seen hurrying to the right to meet his pals. In the next shot he is repeating the movement again.
Continuity mistake: When Superman is about to tilt the Leaning Tower of Pisa, he places his hand with the thumb up. A frame later it's down.
Continuity mistake: When bad Superman punches Clark, he lands half a meter behind a red car hood. In the following shot the hood is by his side.
Continuity mistake: When the Olympic marathon runner holds the torch while running on the track toward the stairs, he has a large upper body build. Also, his shirt has a very noticeable logo that is lying right on his sternum. As he climbs the stairs we see him from behind and this is the last of the real footage from the Olympics. The actor holding the torch, that gets blown out, does not climb the stairs near as gracefully as the Olympic athlete. When they show him from the front, not only does he have very little upper body muscle, but his face is nowhere near the same as the athlete in the stock footage. (01:12:10)
Continuity mistake: After Evil Superman was done melting the mirror in the bar he slowly stood up from the stool to leave the place. The immediate next shot from the sidewalk right outside the bar shows a pedestrian approaching, and as he walks by the establishment Superman can be seen through the window still sitting down at the counter.
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 ★