Revealing mistake: In Houston, when a man is thrown through a truck, notice the ground he falls on: The sand is leveled higher than the rest of the road around, obviously to hide a landing mat. Furthermore, after the fall the man turns around and he's got a bulgy square on the back to help for a safe stunt.
Revealing mistake: In the final scene, Superman is returning the White House's flag to its rightful place, flying over the fountain on the lawn...which is frozen solid in place. Obviously a photo backdrop.
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.
Revealing mistake: There are two external White House shots in the film. The second is a still shot, and should take place at least a few days after the first. However, it is a frame from the earlier shot, with the same person standing in the same spot on the lawn.
Revealing mistake: In the beginning, when Superman is flying to the Eiffel Tower, the last scene that shows him flying towards the tower, you can see the wire Christopher Reeve was attached to as he swoops down. The wire stretches all the way across as Superman glides down.
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.
Revealing mistake: In the first confrontation between Superman and the Zod Squad, Superman gets chased out over the water. In the first two shots in this chase, if you look at the bottom right-hand corner of the screen (at least in the letterboxed version) you can see the wake of the boat that they used to make these two pull-back shots. (01:34:40)
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.
Revealing mistake: Wires holding Superman are seen when he lands on the island to pick up fruit.
Revealing mistake: The fire that comes out of the flame throwers moves at a slow speed though the scene is developing at normal speed.
Revealing mistake: After Superman saves the kid at Niagara Falls, he lands on a lawn nearby. Then wires holding him are visible.
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: 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.
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.
Revealing mistake: In the ice cave, Superman throws a plastic S at Non. The wires moving it are visible.
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.
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.
Revealing mistake: When Zod takes the rifle out of the cop's hand the strings moving the rifle are seen, each by the side of the cop's cowboy hat when the rifle turns red.
Revealing mistake: When Ursa blows the helicopter away, the string holding it is visible.
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