Deleted Scene: 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.
Missing Episode: The film had a running time of 132 minutes in its first release. When restored in 1973, only 125 minutes of film could be found, but they did have the entire soundtrack. The restored version shows publicity photos and stills in place of the missing film elements.
The Other Marty: Almost happened to Sam Jaffe. Columbia's Harry Cohn hated his performance as the High Lama and pushed Capra to screen test Walter Connolly as a replacement. Everyone agreed Connolly's test wasn't very good, so Cohn just had Jaffe reshoot his scenes.
Shangri-La and what it represents longing for a faraway place of beauty, spiritual replenishment, and supernatural longevity stuck around. When Tibet realized that heavy logging of their old-growth forests was causing disastrous floods, they turned to tourism, found that it paid really well, and renovated a village, renaming it Shangri-La.
Throw It In!: Everett Horton improvised the scene when he is startled by the mirror in the lacquer box when Frank Capra asked him to suggest some business for that scene.
Troubled Production: A notable early example. At just over a million dollars, it was the most expensive film Columbia had produced up to that point. Exercising his power as one of the first recipients of the Auteur License, Frank Capra put the film overbudget and overschedule, with lots of location filming (a rarity at the time) and multiple cameras running. His initial cut was six hours (with early talk of splitting it into two parts), then a three-and-a-half-hour cut was previewed but bombed horribly with the audience. Capra shot new scenes and did further cutting, but the studio took it away and did the final cut themselves. The film needed several years to recoup its budget, and this isn't even getting into the later cuts and restorations.
Underage Casting: Obviously, anyone playing the High Lama is going to be about a couple centuries too young for the role, but in the 1937 version Sam Jaffe was only in his 40s and required heavy makeup. Frank Capra tried to cast two different older actors, but they both died before filming.
Box Office Bomb: An iconic flop of its era. Despite a $12 million budget and a massive amount of hype, it only raked in $3 million, leading to the industry nickname Lost Investment. This is also seen as the film that put the coffin in the ground for the post-The Sound of Music "epic movie musical" trend (as opposed to a straight-up Genre-Killer).
After a successful run in the previous two decades, producer Ross Hunter never made another feature film after this, and spent the last few years of his career in TV.
It also effectively ended the songwriting partnership of Burt Bacharach and Hal David, as the stress of working on the film led some long-simmering tensions between the two to finally boil over. They still had success writing with other partners after it, however.
He Also Did: The screenplay was by Larry Kramer. The same Larry Kramer who became a prominent playwright and LGBT activist. It's an Old Shame for him, but since he got paid upfront for the film before it flopped, he made a huge amount of money and became financially secure enough to pursue his other interests.
Keep Circulating the Tapes: Due in part to its "all-time turkey" status, for a long time the only easy way to see it was via late night TV airings, since it was never released on VHS and the only home video release was on LaserDisc in The '90s. Finally it reached DVD in 2011 and Blu-Ray a year after that.
Star-Derailing Role: Downplayed for Liv Ullman; while not her first English-language or even American film, Ross Hunter intended to firmly launch her as an A-list star in Hollywood with this one, but it didn't take. However, her international success continued unabated. In fact, no one's acting career was completely sunk by this movie's failure, even as it was a Creator Killer for Hunter.
Underage Casting: Charles Boyer was in his 70s, so he was closer to the mark as the High Lama than Sam Jaffe.