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.
Dwayne Hickman is best known to TV viewers as the title character in The Many Loves of Dobie Gillis.
Dick Sargent is best known as the second Darin Stephens on Bewitched.
Michael Parks is best known to TV viewers as the laconic title character in the 1969-70 NBC drama Then Came Bronson.
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?
Ellery: Well, Dad, looks like we start all over again.