Citizen Kane was a rare film in that its principal roles were played by actors new to motion pictures. Ten were billed as Mercury Actors, members of the skilled repertory company assembled by Welles for the stage and radio performances of the Mercury Theatre, an independent theater company he founded with Houseman in 1937.:119–120 "He loved to use the Mercury players," wrote biographer Charles Higham, "and consequently he launched several of them on movie careers.":155
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:187 and Sloane was well known for his role on the radio show The Goldbergs.:187 [v] Mercury actor George Coulouris was a star of the stage in New York and London.
Not all of the cast came from the Mercury Players. Welles cast Dorothy Comingore as Susan Alexander Kane. Comingore had never appeared in a film and was a discovery of Charlie Chaplin.:188 Chaplin recommended Comingore to Welles,:170 who then met Comingore at a party in Los Angeles and immediately cast her.:44
Welles had met stage actress Ruth Warrick while visiting New York on a break from Hollywood and remembered her as a good fit for Emily Norton Kane,:188 later saying that she looked the part.:169 Warrick told Carringer that she was struck by the extraordinary resemblance between herself and Welles's mother when she saw a photograph of Beatrice Ives Welles. She characterized her own personal relationship with Welles as motherly.:14
"He trained us for films at the same time that he was training himself," recalled Agnes Moorehead. "Orson believed in good acting, and he realized that rehearsals were needed to get the most from his actors. That was something new in Hollywood: nobody seemed interested in bringing in a group to rehearse before scenes were shot. But Orson knew it was necessary, and we rehearsed every sequence before it was shot.":9
When The March of Time narrator Westbrook Van Voorhis asked for $25,000 to narrate the News on the March sequence, Alland demonstrated his ability to imitate Van Voorhis and Welles cast him.
Welles later said that casting character actor Gino Corrado in the small part of the waiter at the El Rancho broke his heart. Corrado had appeared in many Hollywood films, often as a waiter, and Welles wanted all of the actors to be new to films.:171
Other uncredited roles went to Thomas A. Curran as Teddy Roosevelt in the faux newsreel; Richard Baer as Hillman, a man at Madison Square Garden, and a man in the News on the March screening room; and Alan Ladd, Arthur O'Connell and Louise Currie as reporters at Xanadu. When Currie died September 8, 2013, at age 100, she was believed to have been the film's last surviving cast member. Warrick was the last surviving member of the principal cast at the time of her death in 2005. Sonny Bupp, who played Kane's young son, was the last surviving credited cast member of Citizen Kane when he died in 2007.
Production advisor Miriam Geiger quickly compiled a handmade film textbook for Welles, a practical reference book of film techniques that he studied carefully. He then taught himself filmmaking by matching its visual vocabulary to The Cabinet of Dr. Caligari, which he ordered from the Museum of Modern Art,:173 and films by Frank Capra, René Clair, Fritz Lang, King Vidor:1172:1171 and Jean Renoir.:209 The one film he genuinely studied was John Ford's Stagecoach,:29 which he watched 40 times. "As it turned out, the first day I ever walked onto a set was my first day as a director," Welles said. "I'd learned whatever I knew in the projection room — from Ford. After dinner every night for about a month, I'd run Stagecoach, often with some different technician or department head from the studio, and ask questions. 'How was this done?' 'Why was this done?' It was like going to school.":29
Welles's cinematographer for the film was Gregg Toland, described by Welles as "just then, the number-one cameraman in the world." To Welles's astonishment, Toland visited him at his office and said, "I want you to use me on your picture." He told Welles he had seen some of the Mercury stage productions and wanted to work with someone who had never made a movie.:59 RKO hired Toland on loan from Samuel Goldwyn Productions:10 in the first week of June 1940.:40
"And he never tried to impress us that he was doing any miracles," Welles recalled. "I was calling for things only a beginner would have been ignorant enough to think anybody could ever do, and there he was, doing them.":60 Toland later explained that he wanted to work with Welles because he anticipated the first time director's inexperience and reputation for audacious experimentation in the theater would allow the cinematographer to try new and innovative camera techniques that typical Hollywood films would never allowed him to do.:186 Unaware of filmmaking protocol, Welles adjusted the lights on set as he was accustomed to doing in the theater; Toland quietly re-balanced them, and was angry when one of the crew informed Welles that he was infringing on Toland's responsibilities.:5:33–6:06 During the first few weeks of June Welles had lengthy discussions about the film with Toland and art director Perry Ferguson in the morning, and in the afternoon and evening he worked with actors and revised the script.:69
On June 29, 1940 — a Saturday morning when few inquisitive studio executives would be around — Welles began filming Citizen Kane.:69:107 After the disappointment of having Heart of Darkness cancelled,:30–31 Welles followed Ferguson's suggestion[w]:57 and deceived RKO into believing that he was simply shooting camera tests. "But we were shooting the picture," Welles said, "because we wanted to get started and be already into it before anybody knew about it.":57
At the time RKO executives were pressuring him to agree to direct a film called The Men from Mars, to capitalize on "The War of the Worlds" radio broadcast. Welles said that he would consider making the project but wanted to make a different film first. At this time he did not inform them that he had already begun filming Citizen Kane.:186
The early footage was called "Orson Welles Tests" on all paperwork.:69 The first "test" shot was the News on the March projection room scene, economically filmed in a real studio projection room in darkness that masked many actors who appeared in other roles later in the film.:69:77–78[x] "At $809 Orson did run substantially beyond the test budget of $528 — to create one of the most famous scenes in movie history," wrote Barton Whaley.:107
The next scenes were the El Rancho nightclub scenes and the scene in which Susan attempts suicide.[y]:69 Welles later said that the nightclub set was available after another film had wrapped and that filming took 10 to 12 days to complete. For these scenes Welles had Comingore's throat sprayed with chemicals to give her voice a harsh, raspy tone.:170–171 Other scenes shot in secret included those in which Thompson interviews Leland and Bernstein, which were also shot on sets built for other films.
During production the film was referred to as RKO 281. Most of the filming took place in what is now Stage 19 on the Paramount Pictures lot in Hollywood. There was some location filming at Balboa Park in San Diego and the San Diego Zoo,
In the end of July RKO approved the film and Welles was allowed to officially begin shooting, despite having already been filming “tests” for several weeks. Welles leaked stories to newspaper reporters that the tests had been so good that there was no need to re-shoot them. The first official scene to be shot was the breakfast montage sequence between Kane and his first wife Emily. To strategically save money and appease the RKO executives who opposed him, Welles rehearsed scenes extensively before actually shooting and filmed very few takes of each shot set-up.:193 Welles never shot master shots for any scene after Toland told him that Ford never shot them.:169 To appease the increasingly curious press, Welles threw a cocktail party for selected reporters, promising that they could watch a scene being filmed. When the journalists arrived Welles told them they had “just finished” shooting for the day but still had the party.:193 Welles told the press that he was ahead of schedule (without factoring in the month of "test shooting"), thus discrediting claims that after a year in Hollywood without making a film he was a failure in the film industry.:194
Welles usually worked 16 to 18 hours a day on the film. He often began work at 4 a.m. since the special effects make-up used to age him for certain scenes took up to four hours to apply. Welles used this time to discuss the day's shooting with Toland and other crew members. The special contact lenses used to make Welles look elderly proved very painful, and a doctor was employed to place them into Welles's eyes. Welles had difficulty seeing clearly while wearing them, which caused him to badly cut his wrist when shooting the scene in which Kane breaks up the furniture in Susan's bedroom. While shooting the scene in which Kane shouts at Gettys on the stairs of Susan Alexander's apartment building, Welles fell ten feet; an X-ray revealed two bone chips in his ankle.:194 The injury required him to direct the film from wheelchair for two weeks.:194–195 He eventually wore a steel brace to resume performing on camera; it is visible in the low-angle scene between Kane and Leland after Kane loses the election.[z]:61 For the final scene, a stage at the Selznick studio was equipped with a working furnace, and multiple takes were required to show the sled being put into the fire and the word "Rosebud" consumed. Paul Stewart recalled that on the ninth take the Culver City Fire Department arrived in full gear because the furnace had grown so hot the flue caught fire. "Orson was delighted with the commotion", he said.:8–9
When "Rosebud" was burned, Welles choreographed the scene while he had composer Bernard Herrmann's cue playing on the set.
Unlike Schaefer, many members of RKOs board of governors did not like Welles or the control that his contract gave him.:186 However such board members as Nelson Rockefeller and NBC chief David Sarnoff:1170 were sympathetic to Welles. Throughout production Welles had problems with these executives not respecting his contract’s stipulation of non-interference and several spies arrived on set to report what they saw to the executives. When the executives would sometimes arrive on set unannounced the entire cast and crew would suddenly start playing softball until they left. Before official shooting began the executives intercepted all copies of the script and delayed their delivery to Welles. They had one copy sent to their office in New York, resulting in it being leaked to press.:195
Principal shooting wrapped October 24. Welles then took several weeks off of the film for a lecture tour, during which he also scouted additional locations with Toland and Ferguson. Filming resumed November 15:87 with some re-shoots. Toland had to leave due to a commitment to shoot Howard Hughes' The Outlaw, but Toland's camera crew continued working on the film and Toland was replaced by RKO cinematographer Harry Wild. The final day of shooting on November 30 was Kane's death scene.:85 Welles boasted that he only went 21 days over his official shooting schedule, without factoring in the month of "camera tests.":195 According to RKO records, the film cost $839,727. Its estimated budget had been $723,800.
Citizen Kane was edited by Robert Wise and assistant editor Mark Robson.:85 Both would become successful film directors. Wise was hired after Welles finished shooting the "camera tests" and began officially making the film. Wise said that Welles "had an older editor assigned to him for those tests and evidently he was not too happy and asked to have somebody else. I was roughly Orson’s age and had several good credits.” Wise and Robson began editing the film while it was still shooting and said that they “could tell certainly that we were getting something very special. It was outstanding film day in and day out.”:1210 Welles gave Wise detailed instructions and was usually not present during the film's editing.:109 The film was very well planned out and intentionally shot for such post-production techniques as slow dissolves. The lack of coverage made editing easy since Welles and Toland edited the film "in camera" by leaving few options of how it could be put together.:110 Wise said the breakfast table sequence took weeks to edit and get the correct "timing" and "rhythm" for the whip pans and over-lapping dialogue. The News on the March sequence was edited by RKO's newsreel division to give it authenticity.:110 They used stock footage from Pathé News and the General Film Library.
During post-production Welles and special effects artist Linwood G. Dunn experimented with an optical printer to improve certain scenes that Welles found unsatisfactory from the footage. Whereas Welles was often immediately pleased with Wise's work, he would require Dunn and post-production audio engineer James G. Stewart to re-do their work several times until he was satisfied.:109
Welles hired Bernard Herrmann to compose the film's score. Where most Hollywood film scores were written quickly, in as few as two or three weeks after filming was completed, Herrmann was given 12 weeks to write the music. He had sufficient time to do his own orchestrations and conducting, and worked on the film reel by reel as it was shot and cut. He wrote complete musical pieces for some of the montages, and Welles edited many of the scenes to match their length.