The yacht on which much of the action takes place was the "Zaca", which was rented from its owner, Errol Flynn. Flynn skippered the Zaca between takes, and he can be spotted in the background in a scene outside a cantina.
Orson Welles was very displeased with the score put together by the studio-appointed composer. In a test screening, he put a temp stock score on which was supposed to be a model for the composer. The composer completely disregarded Welles' precisely laid-out blueprint. In particular, the final mirror scene was supposed to be unscored, to create the sense of terror.
Errol Flynn's own pet dachshund is seen in the yacht scenes, since it is Flynn's yacht Zaca in the film. Flynn also did all the aerial photography for that film's yacht scenes and is in the film incognito.
Columbia Pictures chief Harry Cohn thought the movie would ruin his star, Rita Hayworth, and held the release of the picture back for one year. Cohn ordered director Orson Welles to insert "glamour" shots (close-ups) of Hayworth. Because of the success of Hayworth's singing in other films, Cohn ordered filming of the scene where Hayworth sings "Please Don't Kiss Me."
According to Orson Welles, this film grew out of an act of pure desperation. Welles, whose Mercury Theatre company produced a musical version of "Around the World in 80 Days," was in desperate need of money just before the Boston Preview. Mere hours before the show was due to open, the costumes had been impounded and unless Welles could come up with $55,000 to pay outstanding debts, the performance would have to be canceled. Stumbling upon a copy of "If I Die Before I Wake," the novel upon which this film is based, Welles phoned Harry Cohn, instructing him to buy the rights to the novel and offering to write, direct and star in the film so long as Cohn would send $55,000 to Boston within two hours. The money arrived, and the production went on as planned.
Near the end of shooting, Orson Welles told Columbia executives that he wanted a complete set repainted on a Saturday for shooting on Monday. Columbia exec Jack Fier told Welles it was impossible, because of union rules and the expense that would be incurred by calling in a crew of painters to work on a weekend. Welles and several friends broke into the paint department that Saturday and repainted the set themselves, and when they were finished they hung a banner on the set that read "The Only Thing We Have to Fear is Fier Himself". When the union painters arrived at work on Monday and saw that the set had been repainted by someone else, they refused to work, threw a picket line around the studio and threatened to stay on strike until a union crew was paid triple time for the work that had been done (which was why Fier had refused to authorize the work in the first place). To placate the union, Fier agreed to pay them what they wanted but put the cost on Welles' personal bill. In addition, he had the union painters paint a banner saying "All's Well That Ends Welles".
When the film was screened for Columbia president Harry Cohn, he found it so incomprehensible he offered to pay $1,000 to anyone who could explain the plot to him. Later he decided to clarify the film by beginning it with the trial scene and telling the preceding part of the story in flashbacks, but abandoned the plan because so much new footage would have had to be shot it would have nearly doubled the film's cost.
Glenn Anders, who played George Grisby, said he shot the scene in which his character's corpse is carried away on a stretcher before he filmed any of his part as a live person. He signed his final contract for the film while lying on the stretcher.
After distinguished service during WWII in coastal patrol off California, the Zaca was sold out of Errol Flynn's estate and went through years of neglect and disputes in ownership. Rescued from certain destruction and restored by a wealthy Italian businessman, it sails now out of Monte Carlo, and is recognized as one of the finest yachts in the world.