Stuart Erwin
— Dwight Wilson
Dorothy Wilson
— Patricia Merrick, also known as Mlle. Mystera
Warner Oland
— Dr. Paul Cornelius
Dudley Digges
— Horace Merrick
Gertrude Hoffmann
— Mattie (as Gertrude W. Hoffman)
Oscar Apfel
— Chief of Detectives John F. O'Hara
Frank Reicher
— Joe Valerie
Jane Darwell
— Mrs. Marble
Stanley Blystone
— Police Car Driver (uncredited)
Ed Brady
— Paddywagon Cop (uncredited)
Tom Brower
— Detective Schultz (uncredited)
Pat O'Malley
— Detective Brady (uncredited)
Ted Oliver
— Police Desk Sergeant Hamilton (uncredited)
Irving Pichel
— Police Radio Announcer (voice) (uncredited)
Max Wagner
— Policeman in Car (uncredited)