Continuity mistake: Near the end of the film when Lois makes to leave the hospital room after visiting Superman, she takes hold of her son's left hand with her right - meaning he should walk out whilst at her right side, furthest away from the hospital bed. In the next shot, both Lois and her son have swapped positions.
Continuity mistake: In the scene where Superman is trying to prevent the plane from crashing he is holding the nose of the plane and bits of it start to crumble in and fall apart or away. Once the plane is safely on the ground within the ballpark the scene shows the plane from the side where there is no damage to the nose.
Continuity mistake: In the scene when Lex is testing the kryptonite at the basement of the mansion, after the power outage, he is standing directly in front of a square yellow sign. Cut to a wider shot, and he has moved left and Kitty is now in front of the sign. Cut again and Lex is back in his first position.
Continuity mistake: When Superman picks Kitty up from the car to take her to the hospital, her white skirt is way above her knees, revealing the top of her stockings. Superman's hands are on her stockings. When he starts to fly up, the skirt now covers her knees, with his hands on the fabric.