Continuity mistake: After Superman breaks Luthor's door, on Lex's table a map is resting on a sculpture on the left. From a back shot, it isn't.
Audio problem: While flying with Superman, Lois falls down and starts to shout. When he grabs her, her mouth closes slightly and her expression changes, but the loud crying continues.
Revealing mistake: When Superman lands the burglar, wires holding him are visible for a brief moment.
Continuity mistake: When Superman saves the wrecked plane, from the outside shots the window has droplets of water, but from the copilot's POV the glass is clean.
Continuity mistake: The way the word Otisburg is written on Lex's map changes between shots.
Continuity mistake: When Ms. Teschmaker is watching the Metropolis news, the glass by the TV swaps from being behind the sun-lotion cream to in front of it.
Continuity mistake: When Luthor takes the kryptonite out of the box, from a side view he holds it at waist level, from a front shot he holds it at chest level.
Revealing mistake: Under Grand Central, the train that passes by Otis is the same one (5048) that kills the cop.
Revealing mistake: In Grand Central Station, the same extras appear in every scene, no matter where in time or place occurs.
Continuity mistake: When Clark is shot by the mugger, his hat falls down. In the next shot, while Lois is screaming, you can see him taking his hat off.
Continuity mistake: In the wheat field, the clothes inside the cocoon change from being tucked inside a corner to visible.
Continuity mistake: By the craddle, Jor-El's hands are appart, a frame later they're holding the crystal.
Revealing mistake: After Superman saves the cat, he takes off and wires holding him are visible.
Continuity mistake: When the council tells Jor-El not to worry them, a bald man standing in the back changes positions between shots.
Continuity mistake: When baby Clark is greeting the Kents inside the cocoon, Martha's hands change from resting on the sides to up.
Continuity mistake: In the footbal field, one of the megaphones that Clark kicks down appears on the bench in the following shot.
Revealing mistake: After jumping in front of the train, Clark runs leaving a white trace behind. Watch the grass on the lower right and you'll see the scene is speeded up.
Continuity mistake: The position of the baby when his mother holds him by the cradle differs in the wide and close shots.
Continuity mistake: When the truck falls on Jonathan Kent, the way Martha holds him changes between shots.
Continuity mistake: When the player takes Susie with him, a bucket appears from nowhere on the right side of the bench.
Answer: When Krypton exploded, the resulting debris was chemically altered through nuclear fusion, converting it into kryptonite. Bits traveled through space, some eventually ending up on Earth, where it is now lethal to anyone who was from that planet.
raywest ★
Pieces of Krypton that exploded in the Red Sun were made radioactive, and the Red Sun is one of the weaknesses of the Kryptonians.
I thought the Red Sun was poisonous to Kryptonians and caused the remnants of the planet Krypton to become radioactive and also absorb some of the solar energy from the Red Sun. I was under that impression, maybe I'm mistaken.