Revealing mistake: After Superman saves the kid at Niagara Falls, he lands on a lawn nearby. Then wires holding him are visible.
Continuity mistake: After Zod grabs the cop's rifle, a close-up shows the rifle's butt close to the policeman, which is inconsistent with the next shot where the villains are seen many meters away.
Revealing mistake: When Zod is thrown by Superman and passes by Luthor, the stand in is a guy with fluffy hair who looks nothing like Lex.
Continuity mistake: When Non lifts the cops' car, the fat cop starts to tuck his head inside the car, but a frame later it's already in, without having finished the movement.
Continuity mistake: In the big fight in Metropolis Ursa chokes Superman, but a frame later she is 3 meters away from him and her hands are off his neck.
Plot hole: When Superman becomes human for Lois, the molecule chamber nearly rips him apart, he suffers. At the end of the movie, when he tricks out of the evil 3 and turn them into humans with the same radiation, they are just looking around, wondering about the strange lights, but don't suffer at all.
Suggested correction: Well it's established that Superman has altered the machine. Maybe he also reprogrammed it to not leave signs of their powers being removed.
Continuity mistake: Under the elevator when Lois says "Nobel prize" her fingers are completely black, covered in grease. When she starts to say "lil' o" they're just slightly dirty. When Superman saves her they're spotless.
Revealing mistake: There are two times in the New York battle when you can see the actors are being filmed in front of a screen: 1. when Superman kicks Non, Superman in on film and Non is hovering in front of the screen. 2. When Ursa is flying towards Non and Superman with the flagpole, she is hovering in front of the screen.
Continuity mistake: Non attacks the guard, who activates an alarm on his belt. In the wide angle all of his left hand is on the alarm, on the close-up only the index finger. This keeps swapping back and forth.
Revealing mistake: After the Marlboro truck scene, Superman throws Zod and he goes through an office window. The harness to make him fly is visible on his back.
Continuity mistake: When the villains are in front of the sheriff's car he places his hat next to the steering wheel. When the angle changes, the hat is away and he's repeating the movement.
Revealing mistake: In the ice cave, Superman throws a plastic S at Non. The wires moving it are visible.
Continuity mistake: When Clark and Lois land inside the ice cave, the wires holding her are visible.
Continuity mistake: When Superman brings the flag to the White House, the wide shot shows the wind stopping, and the flag coming to a smooth stop. Immediately after, in the close-up, the flag is moving wildly.
Audio problem: When the three villains fly after Superman, they all gather in a circle and one of them says "Wait there". It can't be Ursa because it is too deep and neither Zod's or Non's lips are moving so it is not them. So, who is it?
Continuity mistake: When Clark is lying beaten up on the diner floor, a man in a brown suit next to him disappears.
Continuity mistake: Before the villains arrive at the Daily Planet, Lois' hair is fluffy and her fringe has a straight cut. When the scene ends, her hair is shorter, and her fringe has some stylish cuts. Also, Jimmy's hair alternates between very short and long, due to Richard Lester's reshoots.
Revealing mistake: When Ursa kicks the astronaut into space, she takes a step back and looks upwards. When this happens you can tell that the film is being shown at double speed. Also, when Clark spins the guy on the chair at the end of the film, he snaps back upright far too quickly.
Continuity mistake: When Zod throws the shotgun after discharging it, it lands in front of the police car's back tyre. But when the dumb one goes to pick the gun up, it is now towards the back of the car.
Other mistake: When Lois and Clark leave the Fortress, the car is driving in the wrong lane. This is due to the fact that the shot belongs to a reused scene from the first movie, where an empty car was remotely driven by Lex, who changed lanes all the time.