Jonathan Winters was legendary for his comedic abilities but he had never once, prior to this episode, played a dramatic role. Director Buzz Kulik chose to cast Winters because he not only was physically right for the role of Fats but also because Kulik believed Winters' inexperience in dramatic acting would actually be an asset. In Kulik's words "With a guy like Jack Klugman, you go out and get Jack Warden or somebody like that. However, we determined that here was this guy who was such a brilliant talent, who would bring a kind of freshness, because this was his first time as a dramatic actor."
One of only four The Twilight Zone (1959) episodes to exclusively use, aside from Rod Serling, only 2 onscreen actors. The others are Nervous Man in a Four Dollar Room (1960) starring Joe Mantell and William D. Gordon, Two (1961) starring Elizabeth Montgomery and Charles Bronson. And finally the highly controversial and temporarily banned episode The Encounter (1964) starring Neville Brand and George Takei.
Jackie Gleason was the first choice to play Fats however he turned it down. Gleason had starred as Minnesota Fats in the 1961 pool hall movie "The Hustler (1961)."
In its original concept, the story was to use three actors. Dee Sharon (who is credited but does not appear) played Fats Brown's girlfriend in one or more scenes. At least one of these scenes was filmed before the decision was made to cut her part entirely.