Robbie Lee (Andrey Moss) previously appeared in the season 2 episode 18, "The E.S.P Spy".
Mark Wharton's residence is the same filming location as Harold Van Wick's residence in "Columbo - Playback" and Dave Erhard's residence in "Charlie's Angels - Lady Killer"
Jack Colvin appeared in the series as three different characters - Ed Jasper in "Look Alike" (S2E17), Will Collins in "Hocus-Focus" (S3E15), and Dr. Charles Leith in two "Dark Side of the Moon" episodes (S5E8, E9).