Continuity mistake: In Niagara, Clark moves to the left to warn a kid from falling and a woman next to him lowers her camera. In next shot the camera is up and she repeats the previous movement.
Revealing mistake: The shot of people walking on the street by the Daily Planet is the same one used in Superman I.
Revealing mistake: When Zod says to Ursa to "blow them a kiss my dear" to the helicopter that's firing on them watch as the helicopter is indeed a real military helicopter, then when it loses control it's an obvious model and just before it crashes into the house it's a full size helicopter again but is completely different from the first one that was originally shown.
Audio problem: Before the trio crashed into the Daily Planet (just before the battle with Supes), they were heard flying outside the building. For 3 superbeings with the ability to fly unaided, they sure sound heckuva lot like jet-propelled aircrafts. Jet aircrafts are noisy because of their engines, but superpeople?
Continuity mistake: Clark and Lois are undercover in a hotel in Niagara Falls investigating a Honeymoon scam. There is a scene where Clark is removing money from his pocket to tip a porter. You can plainly see that some of the money is falling on the ground. In the next scene the porter walks away with his tip and the falling money has disappeared.
Continuity mistake: In the opening scene where the three villains destroy the energy crystal and the lights go dark and the rings descend upon them, the light that surrounds them is shown coming down from the ceiling. But, when the dome opens, the light surrounding them shines up from the floor. (As also seen in Superman: The Movie.)
Continuity mistake: The corner in the Fortress of Solitude that exploded looks totally different when we see it at the end of the film.
Plot hole: Lois and a friend of hers are watching Non and Superman fight. But this is totally senseless, because Superman had been flying around Metropolis and chances are slim that he appears in the very same spot to let Lois watch him. And, second and most important, should any doubts arise, the panning angles of the camera never show Lois's building, with the big broken window and the flag poles.
Continuity mistake: There must be a barber's shop or a cosmetics shop somewhere in the Phantom Zone. At the beginning of the first Superman film General Zod's hair looks as if it has been blow-dried, but all through Superman II he looks like he uses wet-look gel.
Revealing mistake: Inside the White House, Non throws a pillar at the soldiers. When it lands on the floor, it starts to move by itself like a puppet, revealing the whole structure was attached to a string.
Continuity mistake: During the fight in Metropolis, General Zod is about to throw a wall part at Superman, it cuts to a street scene with people and there is a "no entry" sign reversed, showing the film was flipped for some reason.
Factual error: The moon has no atmosphere. Yet, the Ursa and Zod are able to speak to the astronauts. We even hear wind as Zod kicks one of the astronauts in the air and snaps his cord. We also hear the explosions when the lunar lander is destroyed. If the moon has no atmosphere, then the super villains can't speak and there should have been no sound in this part of the movie.
Visible crew/equipment: Lighting focus reflected on the cosmonaut's visor.
Continuity mistake: While Superman is crushing Zod's hand, there's a close-up of Non watching the scene in awe. In the following shot, Non's expression has changed to normal.
Continuity mistake: When Ursa throws the White House cop out of the window on the ceiling, the hole in the glass appears before he goes through it.
Revealing mistake: Wires holding Superman are seen when he lands on the island to pick up fruit.
Continuity mistake: When Lois is trapped under the elevator, the wide shots show a thick metal bar close to her throat. In the closeups showing her head and shoulders the bar isn't visible.
Continuity mistake: Superman stands on a flag pole outside one of the windows in Perry's office to defy the 3 villains. When the shot cuts to an outside view of the villains flying, the flag pole has disappeared, and the nearest one is several feet to the left.
Continuity mistake: When Luthor is at Perry's office door, his hair changes from long and messy to short and combed in the next shot.
Other mistake: When Ursa, Non and Zod first arrive on earth, watch out for the horrible lipstick marks on Ursa's teeth as they walk away from the lake.
Answer: In the theatrical cut, nobody really knows why the green crystal restored his powers. However if you watch the Richard Donner cut, it is explained that the green crystal is a communication device that helps Superman talks to the residual essence/spirit/ghost of his father Jor-El. Before he died, Jor-El gave the crystal to his son. Jor-El anticipated that Kal-El might give up his powers, and he also anticipated that Zod might eventually escape the Phantom Zone, so Jor-El lets his son absorb the leftover energy of his spirit, thus restoring all his Kryptonian powers.
Matt Van Gogh