John Shea decided to leave the series after the first season because he was tired of the strenuous commute from New York City to Los Angeles. He returned for four guest spots during seasons two through four.
Dean Cain was the first actor to audition for the part. Series creator Deborah Joy LeVine initially dismissed him as too young, telling her casting director that they were looking for Superman, not Superboy.
Dean Cain (Clark Kent/Superman) and Teri Hatcher (Lois Lane) are the only actors to appear in all 87 episodes of the series.
Gerard Christopher auditioned for the role of Superman, and was chosen by the casting director. However, when the casting director subsequently read Christopher's résumé and discovered that he had previously starred as Superboy in Superboy (1988), she immediately dismissed Christopher. According to Christopher, she told him, "You've done this already!"