Continuity mistake: In prison while Otis repeats what Luthor says he has a cop's hand on his shoulder or not, depending on the shot.
Continuity mistake: When Superman arrives at the broken railroad track the gap is huge, but when he places his body in between the tracks it is exactly Superman's height.
Visible crew/equipment: When the cocoon cradle crashes and the Kents pull-over, lights and bulky object (camera?) are reflected on the driver's door, perfectly visible when he opens the door. Seconds later, rigs and filming equipment are visible on the fender.
Continuity mistake: When baby Clark lifts up the truck, Martha's grip on his husband changes: In the close-up she grabs his chest, but in the wide angle she grabs his ribcage. This changes back and forth several times.
Continuity mistake: While Lex and Otis are talking with the lieutenant and his crew at the bridge, the sun changes between shots.
Continuity mistake: In the extended version, where Martha is preparing breakfast, she places a box of Cheerios on the table. Then she looks out the window at Clark. The shot changes to an exterior shot of her looking out the window, but there is a pitcher of milk next to the box of Cheerios that was not there before.
Continuity mistake: While Lex is telling Superman his plans with the missiles at his home, he is touching his cane with both hands then only then both hands back again.
Revealing mistake: When the helicopter gets jammed on the white railing at the ceiling, Lois is replaced by an obvious dummy that dangles back and forth with no control.
Continuity mistake: While Lois and Superman are being mugged in the alley, Lois kicks the thief and protects herself leaning with her face against the wall and her arms widely spread. A frame later, when Clark grabs the bullet, her arms are close to her head.
Revealing mistake: As Air Force One enters the frame from the right, there appears to be a set of tracks faintly visible under it.
Revealing mistake: When the helicopter is hanging off the roof, a safety securing cable is attached to the fuselage to keep it in place.
Continuity mistake: In the extended version, in the scene where Martha is preparing breakfast, in the interior shot, she places a box of Cheerios on the table. Then she looks out the window at Clark. The shot changes to an exterior shot of her looking out the window, but the angle of the box of Cheerios has changed. (00:38:35)
Continuity mistake: In the extended edition, before Superman enters Lex's lair his hair is short, then when he's being shot at, his hair is much longer and bulkier. When he finally enters the place, it's back to short.
Continuity mistake: The two cops are following Otis at Grand Central Station and two girls, one in yellow, pass by their left side. When the angle changes to a closer one, the girls are in the back and pass by again.
Continuity mistake: Lois exits Perry's office and Clark enters to talk about salary. His hat swaps from facing up to down between shots.
Continuity mistake: When Clark is about to jump in front of the train, there's a crossing sign shaped as an X. Depending on the shot the front upper left part is either bent and about to break, straight, or missing.
Continuity mistake: When the Kent's stop the truck and see the cradle, the sky swaps from sunny and clear to heavily cloudy in a second.
Continuity mistake: When Kent's father pulls over his car, he holds the steering wheel with his right hand on the top. From the side, barely a frame before, he has his left hand on the side.
Continuity mistake: The way the bags are positioned in the Kent's pickup differs between the side and back angles.
Continuity mistake: In Lex Luthor's lair, the bottles to the left of the TV broadcasting the news disappear in the following shot.
Chosen answer: The Council believed that Jor-El was being an alarmist, that the changes in Krypton's core would only result in the planet's magnetic fields shifting rather than the beginnings of a chain reaction that would destroy the world.
Captain Defenestrator