This is the first time that Captain James T. Kirk's middle name of Tiberius, a name first listed in written Star Trek (1966) guides, is revealed onscreen. Although Star Trek: The Animated Series was not considered canon by Gene Roddenberry, many writers of later series helped to canonize several of the show's elements, and the name Tiberius was finally confirmed in Star Trek VI: The Undiscovered Country (1991). David Gerrold would jokingly tell fans that Tiberius was a reference to Robert Graves' "I, Claudius". The name spread amongst fans, and Gerrold added it to the script after approval from Roddenberry. The movie Star Trek (2009) would later provide a backstory to the origin of the name: Tiberius was Kirk's paternal grandfather.
David Gerrold suggested that Nichelle Nichols should do the voice of the entity because of her popularity with "Star Trek" fans.
This episode was originally developed for the first season; however, it was postponed because David Gerrold and D.C. Fontana were disappointed with Gene Roddenberry's frequent changes to the script. Roddenberry added the idea of the godlike entity to the script. Gerrold was originally disappointed with this because he felt the idea had been used enough times on Star Trek (1966); however, he eventually became satisfied with his own final script.
In the commentary track on the DVD of this episode, David Gerrold said the original premise of the show was that, "Spock is very logical and his emotions are under control. What if Spock were prejudiced against something? It would have to be a logical reason for prejudice. It would have to be somebody who is very, very illogical."