Trivia

Although this was the first episode to air on NBC, it was actually the sixth episode produced. NBC chose to air this episode first because they felt that it had more action than any of the first 5 episodes and it also featured a monster.

During the production, Marc Daniels introduced a system in which cast who were not needed on a shoot would go to a "cast table" area and sit with the other actors to practice upcoming scenes, rather than being allowed to return to their dressing rooms. This sped up the filming process, and the producers felt that it also improved the quality of the performances. The cast table system continued to be used throughout the production of The Original Series, even when Daniels was not directing the episode in question.

Grace Lee Whitney considers the arboretum scene of Rand and Sulu as one of her favourite scenes of the series. She recalled that shooting the scene was quite funny, and the entire cast and crew were in a lighthearted atmosphere. Some crude jokes were told in connection with Beauregard and her, and even the puppeteer below the table, Bob Baker, tried to reach for her short skirt with the puppet. Whitney later described this episode as "filled with plenty of horrific and suspenseful moments. It was a great debut episode for the series."

It was Gene Roddenberry's idea to have the creature, in its illusory form, speak Swahili to Uhura. Kathy Fitzgibbon supplied him with the translation. In English, the illusory crewman says "How are you, friend. I think of you, beautiful lady. You should never know loneliness."

For the first time on camera, Uhura wears a red uniform instead of a gold one, from the earlier filmed episodes The Corbomite Maneuver (1966) and Mudd's Women (1966).