In a 1975 magazine interview with Rona Barrett, producer Ross Hunter acknowledged the failure of the soundtrack. "When we hired Bacharach and David to write the songs, we didn't know they were on the verge of dissolving their partnership. When they finally delivered the music, we were already deep into preproduction. We knew it was a bum score, but we couldn't do anything about it."
This movie was the first one Columbia Pictures filmed after it moved onto the Warner Bros. studio lot in 1972, creating The Burbank Studios to facilitate both production companies. The castle set from Camelot (1967) was recycled as Shangri-La. The medieval turrets were removed and replaced with Tibetan gables to simulate Himalayan Buddhist monasteries. Most of the castle's lower levels remained intact, and the courtyard was replaced with layered steppes and fountains. The set remained on the studio's back lot for several years before it was torn down to make way for a new office building.
The film was one of the few mainstream American films of the 1970s never released on VHS in the U.S. A limited-edition laserdisc release in the early 1990s was the only U.S. home video release until 2011, when Sony released the film on DVD.
Michael York has said that despite Ross Hunter's reputation for lush productions, York found the decor tacky. The lamasery scenes were filmed in Burbank during a hot summer, and York began to call the location "Shangri-La in the Smog".
Pierre Cardin put out a line of costume jewelry, watches and belts "inspired by Lost Horizon". Marrakech, Ltd. had a line of "Lost Horizon" shirts for men, Periphery a line of women's attire, Rijir a line of colognes and soaps, and Brown Jordan a line of rattan furniture all designed for that Shangri-La look. Craft Masters put out a paint-by-number set, and Saalfield marketed a "Lost Horizon" coloring book.
Professional vocalists Jerry Whitman and Diana Lee provided the singing voices for Peter Finch and Liv Ullmann, respectively. They also sang on the Disneyland Records release "The World Is A Circle", which featured a handful of songs from this film, plus other show tunes.
Touring back-up singer and session vocalist Jerry Whitman was contractually obligated not to reveal his vocal participation. "They didn't want me capitalizing on it or putting out a press release," Whitman said. "But the movie turned out to be such a bomb, I don't think anyone would care if I talk about it now."
The film was a box-office and critical flop. Esquire called it "The worst movie of the year." Cue critic William Wolf called it "Atrocious... lame-brained... Some $6 million was spent on this worst-of-worst remake".
As of 2015, this marks as the last screenplay for a theatrical film written by Larry Kramer. In Larry Kramer in Love and Anger (2015), the writer reveals that he isn't proud of his script for the movie but acknowledges that the deal he made with producers for this work (along with some other great investments) made him free of financial worries for the rest of his life. He went on to become a successful playwright and LGBT rights activist.