Mysterious Doctor Satan was originally planned as a Superman serial for Republic,[REF] but the license National Comics provided to the Fleischer Studios to make their Superman cartoon series was exclusive and therefore prevented other film companies from using the character at the time, even in a non-animated production.
Mysterious Doctor Satan (serial production number 1095) was filmed between September 20 and October 29, 1940 under the working title Doctor Satan, at a cost of $147,381 [REF].