Voice of the Whistler

Richard Dix John Sinclair / John Carter Lynn Merrick Joan Martin Sinclair Rhys Williams Ernie Sparrow James Cardwell Fred (Doc) Graham Tom Kennedy Ferdinand / Hammerlock Sam Ash Gibson Motor Car Co. Executive (uncredited) Egon Brecher Dr. Rose (replaced by Frank Reicher) (uncredited) Charles Coleman Sinclair's Butler (uncredited)