Bernie Kopell uses same voice for Kleinschmidt character as he used on his regular role as Seigfried, Leader of KAOS in hit 60's show 'Get Smart'.
Joan Fontaine had been among the stars of the movie Voyage to the Bottom of the Sea (1961), which led to the popular series Voyage to the Bottom of the Sea (1964) starring Richard Basehart, who plays her romantic partner here. The same year as the original "Voyage" film, Fontaine and Basehart had first worked together in a TV version of The Light That Failed (1961). Six years before this episode, Fontaine had also been paired with Basehart's series co-star David Hedison in an episode of Cannon (1971) titled The Star (1975).