This episode marked the final appearance of John Hillerman as radio star Simon Brimmer who was 0 for the series doing battle against Ellery Queen.
Ken Berry had previously starred in F Troop and Mayberry RFD.
Norman Fell is best known to TV viewers for his role as tightwad landlord Stanley Roper on Three's Company.
Rudy Vallee and Ellery Queen co-star David Wayne both played villains on Batman. Romero played Lord Marmaduke Fogg and Wayne played the Mad Hatter.
Ellery: Danny, you watch your temper.
Brimmer: (to Wyner) A bit overplayed, wouldn't you say?
Ellery: What happened?
Brimmer: Murder, plain and simple. Tell your father to alert his minions.
Inspector Queen: A record library is the perfect place for a murder. Nobody around.