Kay Kyser
— Himself
Peter Lorre
— Professor Karl Fenninger
Boris Karloff
— Judge Spencer Mainwaring
Béla Lugosi
— Prince Saliano
Helen Parrish
— Janis Bellacrest
Dennis O'Keefe
— Chuck Deems
Alma Kruger
— Aunt Margo Bellacrest
Joseph Eggenton
— Jurgen
Ginny Simms
— Herself
Harry Babbitt
— Himself
M.A. Bogue
— Ish Kabibble
Sully Mason
— Himself
Mary Bovard
— Mary (uncredited)
Jeff Corey
— Mr. Corey (uncredited)
Louise Currie
— Marion (uncredited)
Bess Flowers
— Lady In Taxi (uncredited)
Jeanne Houser
— Jean (uncredited)
Richard Kipling
— Script Man (uncredited)
Eleanor Lawson
— Ms. Gaby Lawson (uncredited)
Larry McGrath
— Apartment Complainer (uncredited)
Frank Mills
— Cabbie (uncredited)
Mimi Montaye
— Mimi (uncredited)
Dorothy Moore
— Penny (uncredited)
Leonard Mudie
— Real Karl Fenninger (uncredited)
Joseph North
— Servant (uncredited)
Frank O'Connor
— Apartment Responder (uncredited)
Beulah Parkington
— Mother (uncredited)
Jane Patten
— Jane (uncredited)
Eugenia Rafee
— French Maid (uncredited)
William Telaak
— Mac (uncredited)