Producer Bryan Foy was one of many who felt that the film was too long. Upon hearing that 40 minutes had to be excised, Foy is alleged to have said: "Just throw all the footage up in the air and grab everything but 40 minutes."
RKO chopped 50 minutes of the film and added a happy ending while Orson Welles was out of the country. The footage was subsequently destroyed; the only record of the removed scenes is the cutting continuity transcript.
Sets were re-used by Val Lewton in Cat People and The Curse of the Cat People to help save production costs resulting from a ridiculously small budget.
Several cast members in studio records/casting call lists apparently were eliminated during the final editing process. These were (with their character names): Jesse Graves (Servant), Lillian Nicholson (Landlady), Robert Pittard (Charles Johnson) and Sam Rice (Attendee at Funeral). Don Dillaway (Wilbur Minafer) is not mentioned in Welles' oral credits, but he appears in three scenes in the opening minutes of the film: As Isabel and Wilbur emerge from a store, Isabel spurns suitor Eugene's attentions; Wilbur reads aloud a letter complaining about son George's misbehavior as George, Major Amberson, and Isabel listen; and Wilbur has lines in several shots of the ball scene.
The consensus of opinion according to nearly everyone who saw the original conclusion - which included a tour of the decaying Amberson mansion - was that it was much more powerful than the tacked-on "happy" ending.
The earliest Morgan Automobile shown in the film is actually an 1892 Philion Road Carriage, one of the oldest existing American built cars and the only one produced. It can still be seen at the National Automobile Museum in Reno, Nevada.
The first major film to have nearly all its credits narrated rather than appear on screen.
The main poster for the Ambersons was designed by Norman Rockwell.
The preview of the movie occurred a short time after Pearl Harbor. Because of this, most of the audience review cards stated that they didn't want to see a depressing movie, and that it should have more laughs and a happy ending. With Orson Welles out of the country, the production team had to make the cuts and changes without his input.
The re-cutting of this film caused a deep rift in Orson Welles' friendships with Robert Wise and Joseph Cotten. Cotten later wrote several letters of apology to Welles, and the two later reconciled. Welles and Wise, however, remained on acrimonious terms for some 42 years until Wise was invited to come to the stage by Gil Cates when the Directors Guild honored Welles with its Lifetime Achievement Award in 1984. The former rivals ended up shaking hands as the crowd rewarded them with a standing ovation.
The scenes with the automobile ride with the snow were filmed in an abandoned icehouse instead of the RKO stage reserved for such shots. However, it took much longer than anticipated because the equipment kept having problems that were brought on by the cold (film jamming because of frozen condensation, lenses fogging up, etc.). Because of this everyone involved, except for Orson Welles, contracted a terrible head cold.
The set for the Ambersons mansion was one of the most elaborate and expensive sets ever built at the time. RKO would utilize the standing set for other films.
To persuade RKO head George Schaefer to approve this film as a follow-up to Citizen Kane, Welles played him the Mercury Theater of the Air radio version. It is claimed that Schaefer fell asleep during this. Nevertheless, he greenlighted the film for $1 million, an unheard-of move for a studio whose policy was not to make films that cost more than $750,000.
Twenty years later, Welles was still planning an epilogue starring the older Joseph Cotten, Anne Baxter, Agnes Moorehead and Tim Holt.
Welles demanded that the inside of the Ambersons mansion be built as if it was a real house, with continuous rooms of four walls and ceilings. This enabled his camera to roam around the house freely and shoot from any angle.
Welles later described the 88 minute version as if "it had been edited by a lawnmower".
While Welles would direct "Ambersons" during the day, at the same time each night he would act his part of a Turkish policeman in Norman Foster's film Journey Into Fear.