Visible crew/equipment: Ursa throws the sewer lid at Superman sending him flying backwards into the car windshield. Watch the sewer lid carefully when Superman actually hits the windshield. You can see that the sewer lid was actually attached to a belt around his waist so that it would stay in place for the shots where he is flying backward through the air. (01:39:50)
Revealing mistake: When Zod lifts the boy's father with the beam of white energy, watch closely when he raises him up past the telephone pole...he 'clips' right through it, or rather the pole clips through him, as if he is transparent.
Visible crew/equipment: When Superman is fighting Non under the New York Streets (in the sewers), manhole covers start to jet up in the sky. When the first manhole cover shoots up you can quite clearly see the gas tube in the hole and the gas cylinder attached to the cover.
Visible crew/equipment: In the shot where Zod walks on the lake's water, there is a platform visible just under the water's surface.
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.
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.
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: Before the villains arrive at the Daily Planet, Lois's 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.
Other mistake: In the long shot of the Niagara Falls scene, the kid's right arm is way too long.
Revealing mistake: The 3 villains break through the Daily Planet window and fly around the city. Before Zod stops by a beam, Non becomes transparent.
Continuity mistake: After Non smashes Superman against a metal structure which gets totally crumpled, Superman stands up and the structure is undamaged.
Revealing mistake: Near the end of the film when the 3 villains enter the fortress, Ursa throws Lex Luther off her back and flies away. You can clearly see that it was a stuntman and not Gene Hackman.
Revealing mistake: During the big fight in Metropolis, the close-up of the pram shows its empty. It must a very expensive pram for the mother to protect it in such a heroic way.
Visible crew/equipment: When Non crashes Perry against the ceiling, a crew member's hand is seen holding Perry.
Revealing mistake: When Lois jumps in the river, she is replaced by a very obvious mannequin that floats stiff. Furthermore, the current tilts the dummy and its two arms bent like a sex doll's are perfectly visible.
Continuity mistake: During the big street fight, Ursa grabs a flag pole. It is either in the shadows or lit, depending on the angle.
Continuity mistake: When Zod launches Boog through the cafe window, he lands a couple meters away from the cop, but a shot later he's at his feet.
Visible crew/equipment: When the villains enter the fortress, the moving shadow of the crane used to make them fly is visible when the last villain flies towards the upper left quadrant.
Revealing mistake: When Ursa throws the sewer lid at Superman a sticky object protrudes from his back, revealing the mechanism that pulled him backwards.
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