While shooting the "Across the Wide Missouri" with Clark Gable in 1951, Ricardo Montalban suffered a back injury that would cause him pain for the rest of his life. The injury left him with a noticeable limp that is visible in the scene in which he and Florence Henderson walk down a path together.
While on break from filming this series, Ricardo Montalban filmed Star Trek II: The Wrath of Khan (1982). Guest star José Ferrer's son, Miguel Ferrer, made a brief appearance in the next film, Star Trek III: The Search for Spock (1984).