Continuity mistake: Luthor extends his arm with a dollar bill in hand for Nuclear Man to light. From the front his arm is fully extended. From behind it isn't.
Continuity mistake: When the SWAT van is turning around, the cars on the street are different than the ones in previous shots (try to find the destroyed taxi cabs that collided).
Continuity mistake: When Nuclear Man is thrown down the chimney, he is unconscious with his arms and head looking down. A frame later he is stiff, with his arms up and pointing to the sky.
Revealing mistake: While flying together, Superman let's go of Lois and she plummets at first, but then, with the snowy mountains behind, she's able to float on air and keep on moving at the same time for 5 seconds.
Continuity mistake: When the crowd follows Superman to the UN the mounted cop changes from being on the left side to the right.
Revealing mistake: While the subway train is gone wild, there's a brief shot of bystanders on the platform. Then the train keeps going on for several seconds, and when it finally comes to a stop the actors are the same ones used previously.
Revealing mistake: When Lenny's car, with the cops in it, flies into the air you can see it's empty.
Continuity mistake: When Nuclear Man walks towards the newspaper on the desk, the phone cable's position changes through shots.
Continuity mistake: Superman crosses flying the Golden Gate Bridge together with Lois, heading close to the bay area. Half a second later they are next to the bridge again.
Continuity mistake: When Superman stops the subway train, there's a black man with a moustache, red shirt and a gabardine suit in the first line. Then he manages to appear meters behind, despite the jam on the platform. Then Lois appears behind him. Then she magically disappears and he appears back on the front.
Continuity mistake: Lois hands the newspaper to Clark, with the headline "Superman says drop dead to kid", and a guy in a red shirt in the background stands up and leaves, followed by a bunch of people behind; in the following angle he is sitting down and the whole choreography is repeated.
Continuity mistake: After Clark takes the green crystal from the hole on the ground and hides it, the cloth covering the hole has a different position to how it looked a second before.
Continuity mistake: When Superman is out on the balcony with Lois, a tall, wide building is reflected on the glass behind, but when the angle changes to Superman's POV the building is gone, and now there's just a vast open space and a thin skyscraper.
Continuity mistake: When the Soviet missile is about to be launched, the sky changes from daytime to dusk.
Continuity mistake: Before Nuclear Man burns Luthor's dollar bill, Luthor looks to his right, immediately after, the shot from behind shows him looking straight forward.
Continuity mistake: During the volcano scene, a girl is holding on to the priest's arm at wrist level. A split of a second later her grip changes to above the elbow level.
Plot hole: Superman dropping Nuclear Man in the area of a nuclear plant would have made him much stronger, since that is giving him a lot of nuclear energy. Instead he is killed.
Continuity mistake: When the window shops explode, the grey car close to them disappears in the following shot.
Continuity mistake: When Superman rescues Lucy in space she is placed on his right side. A frame later she is on the left.
Continuity mistake: In the hotel suite, the kitchen door is always open, except for the moment when Superman has to look through it, when the door appears magically shut.
Suggested correction: Dropping nuclear man in to a nuclear power plant isn't as silly as it seems, assuming that the nuclear power is far greater than nuclear man he would simply be absorbed by it rather than growing stronger.
That never got shown and the fact that he was able to make a volcano erupt speaks volumes.
Athletic Jason