Bud Abbott as Cuthbert Greenway / Dr. Ralph Greenway

Lou Costello as Horatio Prim

Marjorie Reynolds as Melody Allen

Binnie Barnes as Mildred Dean

John Shelton as Sheldon Gage

Gale Sondergaard as Emily

Lynn Baggett as June Prescott

Jess Barker as Thomas Danbury

Ann Gillis as Nora O'Leary

Donald MacBride as Lt. Mason

William Hall as Sgt. Conners

Robert Barrat as Maj. Putnam

Rex Lease as Sgt. Makepeace

Kirk Alyn as Dandy at Party (uncredited)

Harry Brown as Second Sergeant (uncredited)

George M. Carleton as Museum Guard (uncredited)

Wheaton Chambers as Bill - Museum Guard (uncredited)

James Conaty as Party Guest (uncredited)

John Crawford as Dandy at Party (uncredited)

Vernon Downing as Leigh - Traitor (uncredited)

Marjorie Eaton as Bessie - Danbury's Maid (uncredited)

Myron Healey as Dandy at Party (uncredited)

Boyd Irwin as Cranwell - Traitor (uncredited)

Selmer Jackson as Mr. Dibbs - Museum Curator (uncredited)

William H. O'Brien as Danbury Servant (uncredited)

Scott Thomson as Dandy at Party (uncredited)

Harry Woolman as Motorcycle Rider (uncredited)