After Margot Kidder expressed her disgust about the firing of Richard Donner to producers Alexander Salkind and Ilya Salkind, her role was cut to 12 lines and less than five minutes of screen time. In the film's 2006 DVD commentary, Ilya Salkind says there was little need for Lois Lane in this movie because her relationship with Superman ended at the end of Superman II (1980).
Christopher Reeve was not happy with the film, and often expressed in interviews that he was mostly disappointed in how it turned out. He initially swore never to play the role again, saying he was aging out of the role. He was persuaded to make Superman IV: The Quest for Peace (1987) in exchange for more input on the script.
This is the first time Christopher Reeve had top billing in a Superman movie. In Superman (1978) he was behind Marlon Brando and Gene Hackman. In Superman II (1980) he was behind Hackman.
When it was first revealed to producers that Lana Lang would be a single mother, a comic book was quickly written explaining how Lana came to be in that situation.
Richard Pryor was said to have been cast by the Salkinds due to comments he made on The Tonight Show Starring Johnny Carson (1962). During an interview segment, Pryor excitedly told Carson he was looking forward to seeing Superman II (1980). His casting would also help attract Richard Lester to return and direct, as Lester was eager to work with Pryor, who appealed to his comedic sensibilities.
Aaron Smolinski: (at around 6 mins) Aaron Smolinski who played baby Clark Kent in Superman (1978) appears uncredited as a little boy waiting outside a photo booth while Clark Kent is changing into Superman.
Paul Weston: (at around 5 mins) accidentally breaks off the door handle in an attempt to rescue the drowning driver from the car. The stunt coordinator was Terence Stamp's double in Superman II (1980).