Kay Kyser as Himself

Peter Lorre as Professor Karl Fenninger

Boris Karloff as Judge Spencer Mainwaring

Bela Lugosi as Prince Saliano

Helen Parrish as Janis Bellacrest

Dennis O'Keefe as Chuck Deems

Alma Kruger as Aunt Margo Bellacrest

Joseph Eggenton as Jurgen

Ginny Simms as Herself

Harry Babbitt as Himself

M.A. Bogue as Ish Kabibble

Sully Mason as Himself

Mary Bovard as Mary (uncredited)

Jeff Corey as Mr. Corey (uncredited)

Louise Currie as Marion (uncredited)

Bess Flowers as Lady In Taxi (uncredited)

Jeanne Houser as Jean (uncredited)

Richard Kipling as Script Man (uncredited)

Eleanor Lawson as Ms. Gaby Lawson (uncredited)

Larry McGrath as Apartment Complainer (uncredited)

Frank Mills as Cabbie (uncredited)

Mimi Montaye as Mimi (uncredited)

Dorothy Moore as Penny (uncredited)

Leonard Mudie as Real Karl Fenninger (uncredited)

Joseph North as Servant (uncredited)

Frank O'Connor as Apartment Responder (uncredited)

Beulah Parkington as Mother (uncredited)

Jane Patten as Jane (uncredited)

Eugenia Rafee as French Maid (uncredited)

William Telaak as Mac (uncredited)

Joan Warner as Joan (uncredited)

Guy Webster as Infant (uncredited)

Mary Martha Wood as Georgia (uncredited)