The six letters in the word Shazam stood for the six Elders who granted Billy their powers: Solomon, Hercules, Atlas, Zeus, Achilles and Mercury.
Jackson Bostwick was fired two episodes into Season 2 and replaced with John Davey. Bostwick had been injured during filming, got medical treatment, and was advised to stay home for a few days to recuperate. Producers accused him of holding out for a higher salary. Bostwick successfully sued Filmation, which was forced to pay his full salary for the entire series, including all of its reruns, on CBS.
Billy Batson's work in radio from the comics was only mentioned once in this series. A brief line spoken by Billy in its first episode explained that radio station WHIZ had sent him on a roving assignment to do stories about American youth, with Mentor as an advisor.
Jackson Bostwick said that when he was fired from the series, the producers told him that since it was a kid's show, most viewers would not notice another actor replacing him. Bostwick believed that most kids were smart enough to tell the difference, and he was largely proved correct.
Because this show and Isis (1975) were produced by the same company, they often had crossover episodes.