Frank Capra hated screen tests; scripts were developed with specific actors in mind. Ronald Colman was first choice to play Conway from the very beginning. It was only over who should play the High Lama that he had problems and had to resort to screen tests.
Despite the persistent rumor that Walter Connolly was tested for the role of the High Lama, this was vehemently denied by Frank Capra. Only two actors were considered for the role before Sam Jaffe. English actor A.E. Anson was actually tested but died two days after the it was made. Henry B. Walthall was scheduled to be tested but died before one could be made. The third test was of Jaffe, and he got the part. Capra has been quoted as saying that Connolly was considered for the Thomas Mitchell role, but was committed to another project. Capra added that Connolly and Charles Laughton, who was also rumored for the part, were both too fat to play a 200-year-old ascetic.
Frank Capra's first cut of the film ran for 6 hours. The first public preview took place in Santa Barbara when the film ran for 3 1/2 hours. Re-shooting and re-cutting followed immediately after this disastrous preview.
Many scenes were shot at the Los Angeles Ice and Cold Storage Warehouse where Capra had 13,000 square feet of refrigerated space at his disposal. Nearly four miles of ammonia piping cooled the soundstage. Cinematographer Joseph Walker experienced a lot of problems in this location as the extreme cold created static electricity which damaged his film stock.
The California State Censor Board insisted on having two signed affidavits from Columbia that the model doubling for Jane Wyatt in her nude bathing scene had her breasts covered. The affidavits were duly supplied though the model in question apparently was indeed bare-breasted, though as the scene is in long shot it's virtually impossible to tell.
The Lamasery set was, at the time, the largest single standing set in terms of square feet built for a motion picture of the sound era. The set was built on the Columbia ranch in Burbank with the rear of the Lamasery backing up to the intersection of Verdugo Avenue and Hollywood Way.
Jane Wyatt, "Sondra", stated that the deletion of the High Lama's speech about peace, during Robert's first meeting with Father Pero ( Sam Jaffe) was done so at the request of the US government because.of the films release in the looming shadows of WW2. Ms. Wyatt stated they wanted no views of world peace so that young men would be in the "bang, bang, bang" mode. (available on the movie's recovered sound track & pieced into the re-release with these corrections) Ms. Wyatt, during the administration of president Franklin Roosevelt, was requested by them to arrange the performance of the Bolshoi Ballet during the war. This resulted with her being blackballed during the Senator Joe McCarthy era castigation of American citizens, who were supposedly "Red" (Communists) and not "true" citizens.
Studio head Harry Cohn didn't like Sam Jaffe's performance as the High Lama and insisted that Capra shoot it with another actor. Capra had to submit to this request and a test with Walter Connolly was made, with Cohn even insisting on an expensive new set being built specially for it. Despite loading the dice in Connolly's favor, the consensus was that his test wasn't anywhere near as good. So Jaffe won the part back, though he still had to re-shoot all his scenes as they were deemed to be far too lengthy and wordy.
Soundman Edward Bernds came up with the idea of achieving a faster, barbaric tempo for the previously slow-moving refueling scene by having the tribesmen hack off the tops of the gasoline cans with bayonets and slosh the gasoline out. Frank Capra liked the idea and included it.
The part of the paleontologist was not in the original novel but was developed for Edward Everett Horton by Frank Capra. Horton improvised the scene when he is startled by the mirror in the lacquer box when Capra asked him to suggest some business for that scene.
Ronald Colman recorded a audio version of the story for Decca Records on September 15 & 16, 1944. Directed by George Wells with music by Victor Young, the story was told over six sides of a three disc 78 rpm album (released as Decca DA-402). The recording resembled Hilton's original novel more than the film.
The trivia item below may give away important plot points.
Originally there was an opening prologue in which a weary Ronald Colman on a cruise ship is prompted to tell his amazing story of the land of Shangri-La. Although alluded to in the closing passages of the film, no footage of this prologue has ever been found. Frank Capra claimed he burned it.