Stuart Erwin as Dwight Wilson

Dorothy Wilson as Patricia Merrick, also known as Mlle. Mystera

Warner Oland as Dr. Paul Cornelius

Dudley Digges as Horace Merrick

Gertrude Hoffmann as Mattie (as Gertrude W. Hoffman)

Oscar Apfel as Chief of Detectives John F. O'Hara

Frank Reicher as Joe Valerie

Jane Darwell as Mrs. Marble

Stanley Blystone as Police Car Driver (uncredited)

Ed Brady as Paddywagon Cop (uncredited)

Tom Brower as Detective Schultz (uncredited)

Pat O'Malley as Detective Brady (uncredited)

Ted Oliver as Police Desk Sergeant Hamilton (uncredited)

Irving Pichel as Police Radio Announcer (voice) (uncredited)

Max Wagner as Policeman in Car (uncredited)