In the first season, particularly in Never Wave Goodbye: Part 1 (1963), Lt. Gerard's wife, played by Rachel Ames, is named Ann Gerard. In this episode, the character's name has been changed to Marie Lindsey Gerard.
This episode was originally written as an hour-long episode; but the series associate producer/co-producer, George Eckstein, asked writer Anthony Wilson to expand it into a two-part episode because he liked the script.
Barbara Rush and David Janssen have appeared together in several productions, perhaps most notably for the distinctions between this collaboration and the made-for-TV cult classic Moon of the Wolf (1972) where David Janssen plays the Sheriff hunting a murderous werewolf and Barbara Rush, a prospective victim, assists in the capture.
Bill Zuckert, who plays a police sergeant here, played many such roles in law enforcement during his acting career, even getting a promotion of sorts to the recurring role of Police Chief Segal in the short-lived TV sitcom Captain Nice (1967).
This is the fourth of five appearances Bill Zuckert makes in the series, each time playing a different character.