Sadly, guest star Sal Mineo was stabbed to death on February 12, 1976, just 18 days after this episode aired.
Interestingly enough, Cesar Romero and Ellery Queen co-star David Wayne both played villains on Batman. Romero played the Joker and Wayne played the Mad Hatter.
Dick Sargent is best known as the second Darin Stephens on Bewitched.
Inspector Queen: (about the missing witness) With that information we couldn't find Harry Truman in the White House.
Ellery: Hold it, Flanningan. I'm going alone.
Flannigan: Not on your press pass, Junior.
Ellery: You can stay in the hall while I talk to her.
Flannigan: For a story like this I'll stay in the broom closet.
Inspector Queen: Flannigan, don't you have someplace to go?
Flannigan: (to Velie) Let go of me, you big ape.
Inspector Queen: We know all about your reputation, Flannigan.
Ellery: Jimmy, who won the Daily Double?
Jimmy: I don't bet the Daily Double.
Inspector Queen: (about Armand) Cocky old bird, isn't he?