Four science-fiction icons appear in this episode, beginning with star Gene Barry, who earned his sci-fi creds twenty years earlier headlining The War of the Worlds (1953). Ed Bishop (Wayne) appeared in 2001: A Space Odyssey (1968) and had recently starred in UFO (1970). And finally, Barry Morse (Mr. Parminter) and Catherine Schell (Diana) would both go on to co-star in Space: 1999 (1975). Morse can also boast of memorable roles in A Piano in the House (1962), Controlled Experiment (1964), and The Life Seekers (1968).
The title is a play on a line from the 1945 song "It's Been a Long, Long Time" by Jule Styne and Sammy Kahn: "Kiss me once, then kiss me twice, then kiss me once again, it's been a long, long time."
Although they share no scenes together in this episode, Barry Morse (Mr. Parminter) and Ed Bishop (Wayne) would later appear together in Whoops Apocalypse (1982).