The film represents the feature film debuts of William Alland, Ray Collins, Joseph Cotten, Agnes Moorehead, Erskine Sanford, Everett Sloane, Paul Stewart, and Welles himself. Despite never having appeared in feature films, some of the cast members were already well known to the public. Cotten had recently become a Broadway star in the hit play "The Philadelphia Story" with Katharine Hepburn and Sloane was well known for his role on the radio show "The Goldbergs". Mercury actor George Coulouris was a star of the stage in New York and London.