On his first day on the set, Marlon Brando suggested to Richard Donner that the cameras roll during rehearsal. Brando reportedly said, "Who knows? We might get lucky." According to Donner, that very first take was the one that was used in the finished film. Brando was notoriously lazy and was constantly pulling little stunts like this to lessen his workload. Christopher Reeve even complained about it in interviews, saying Brando was "phoning it in and it shows!"
To obtain the musculature to convincingly play Superman, Christopher Reeve underwent a bodybuilding regime supervised by David Prowse, the man who played Darth Vader in the original "Star Wars" trilogy. While they initially got along quite well, Reeve fired Prowse after the bodybuilder suddenly left the country for ten days without warning or explanation. Prowse also auditioned for both Superman and Non.
Clark Kent and Superman's hair part on opposite sides.
The helicopter scene was intended to be shot on the top of the then Pan Am building, until a real-life accident on the heliport killed several passengers as well as a pedestrian from a falling helicopter blade on May 16, 1977.
Richard Donner was disgusted that production designer John Barry and cinematographer Geoffrey Unsworth received no recognition from the Academy for their work on this film. He was particularly aggrieved that one of the nominees for Best Art Direction was Suite California (1978), which merely duplicated an existing hotel, while Barry created an entire fictional city and a fortress in the Arctic.
Noel Neill: (at around 28 mins) Lois Lane's mother. Neill played Lois Lane in Superman (1948), Atom Man vs. Superman (1950) and Adventures of Superman (1952). She appears when the young Lois sees Clark Kent running extremely fast from a train window.
Kirk Alyn: (at around 28 mins) Lois Lane's father. Alyn played Superman in Superman (1948) and Atom Man vs. Superman (1950). He appears when the young Lois sees Clark Kent running extremely fast from a train window.
Larry Hagman: (at around 1h 35 mins) The Major, after Miss Teschmacher's car "accident", when Lex Luthor reprograms the nuclear missile.
Richard Donner: (at around 1h 22 mins) [expanded version] the skeptical man who talks to Clark Kent in front of the televisions, right after the first appearance of Superman.