Although this is the first and only time Helen Broderick played Hildegarde Withers in the six picture series, James Gleason played Inspector Oscar Piper in all of them.
This the third Miss Withers movie for Bavarian Gustav von Seyffertitz. Of interest is that he played different characters in the films. He played both Von Donnen (the Police Lab man) and Dr. Bloom (the coroner} in The Penguin Pool Mystery (1932) (the first film), Dr. Max Von Immen (the Coroner) in Murder on the Blackboard (1934), and here in the fourth film, he is again Dr. Bloom.
Miss Withers does say that she and "Mr. Jones" were out walking when they found the wandering horse.
Despite being in over a hundred films during the 1930s and 1940s, Willie Best rarely was credited using his own name. This is one of only six films where he actually receives cast credit by his actual name instead of "Sleep 'n' Eat".
The American Experience documentary The Battle Over Citizen Kane (1996) contains a street shot of the Rialto Theatre in New York at which this movie is playing. The marquee gives "Jimmie Gleason" top billing; price of admission was 25 cents.