Orson Welles filmed a trailer that lasted nine minutes and featured several shots of a topless Oja Kodar. The trailer was rejected by the US distributors.
Actress Oja Kodar, who appears in a muse-like fashion in this film, was Orson Welles' girlfriend at the time.
An excerpt of Orson Welles' legendary 1938 'War of the Worlds' broadcast was re-created for this film; however, none of the dialogue heard in the movie actually matches what was heard on the original radio broadcast.
Hidden within a montage of footage of Howard Hughes is one brief shot of a man disembarking from a ship who looks similar to Hughes; it actually is the actor Don Ameche.
Originally, Orson Welles was going to call the film "Fake", and then, for several months, insisted that it would be called "?". Eventually, the final title was settled not long before the film's opening.