According to director Lee Sholem, both Phyllis Coates and George Reeves were knocked out cold on the same day in fights involving stuntmen.
Kirk Alyn, who played Superman in Superman (1948) and Atom Man vs. Superman (1950), was originally to have reprised his role, but he wanted too much money.
Over a year after release, the film was split up and used to make a "two-parter" to close the first season of Superman - Retter in der Not (1952): The Unknown People: Part I (1954) and The Unknown People: Part II (1954). However, the television version discarded the musical score by Darrell Calker and replaced it with music from earlier episodes of the TV series. All references to the alien creatures as "Mole Men" were edited out of the TV version, and a chase scene was trimmed.
This was the first feature-length film based on "DC Comics" (although others such as Batman and even Superman himself had had theatrical serials).
The film was included as a special feature on the fourth disc of the Christopher Reeve Superman Collection and the Complete Superman Collection DVD.