Continuity mistake: When the villains are trapped in the phantom zone (filmed by Richard Donner) Zod, Non and Ursa (from left to right) are tightly pressed against a glass. When the elevator explodes and are about to be released (filmed by Richard Lester) not only are they not pressed, but neither in line, having changed positions (and looks, as already listed): Non now stands above Zod and Ursa.
Continuity mistake: In Krypton when Non breaks the guard's neck the guard presses an emergency button. In the wide angle all of his fingers are extended, but in the close-up only the index is. This changes back and forth.
Revealing mistake: The villains send cars flying through the air. This was achieved with detailed scale model cars in a scale model Metropolis. But in order to mimic the blown-away citizens they use cheap mannequins that move on some sort of conveyor belt. (01:43:50)
Revealing mistake: When the villains blow away the stuff in Metropolis, the fire hydrant falls down and reveals it wasn't fixed to the ground, a blatant prop.
Audio problem: When Ursa lifts the bus she mumbles and laughs, but her mouth is closed.
Revealing mistake: At the Fortress, when the villains and Superman play the appearing/disappearing trick, there's a shot with 4 Supermen onscreen, a special effect which was achieved with stand-ins. The one in front of Zod, and especially the one next to Lois look nothing like Christopher Reeve.
Continuity mistake: At the Fortress, when the 3 villains extend their arms to send a laser beam to Superman, there's a very brief shot on Ursa and her hair style is completely different. Very short and with her forehead very clear.
Continuity mistake: When Superman is putting the antenna back in place, watch the right of the platform with a bunch of metal parts and cables sparking. In the closeup they disappear.
Continuity mistake: The branch that Superman cuts to save Lois from drowning swaps from bright milky chocolate colour to pale dark brown depending on the shot.
Continuity mistake: In the balloon, after Luthor says "Due North", Teschmaker's arm swaps from raised to lowered.
Revealing mistake: When Luthor is about to climb up the balloon his bald cap wrinkles by his nape.
Revealing mistake: In the prison laundry, Luthor's bald cap is very noticeable, especially by his sideburns.
Continuity mistake: When Lois is cutting oranges the glass jumps from being on the right side of the table to being on the far left.
Continuity mistake: When Superman is crossing the street and a taxi crashes against him, the passers-by are not continuous between shots. Check the African American girl in a pink dress who appears randomly on every single corner of the streets around.
Revealing mistake: When the phantom zone explodes it is a cheap pencil drawing animation.
Continuity mistake: After Lois asks the Paris spokesperson about the bomb he turns around and talks to her. Then it suddenly cuts to a closeup of his face and he's now talking to the journalists that were on the left, without having turned his head or body.
Continuity mistake: At the Eiffel Tower Lois approaches the spokesperson, cut to a wide angle where he is facing left. Then as she arrives there's a close up of him turning around. Then back to the previous wide angle where he is facing left again.
Continuity mistake: Perry White is telling Clark about the terrorists while composing the headlines. Note the cut-out of the word IN under Paris. It swaps from straight to slanted between angles.
Revealing mistake: When Luthor and Teschmaker are in the balloon, in the wide angle they both become coloured green due to the blue screen effect.
Visible crew/equipment: There is a moving boom mic above Clark when he talks to Mr. White about the terrorists in Paris. (The Ultimate Collector´s Edition Box Set).
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