At the early stages of production, author-producer Tom Tryon wanted Ingrid Bergman for the role of Ada (the Grandmother), and Mark Lester for the dual roles of Niles and Holland. When Bergman passed due to a previous stage commitment, Uta Hagen was hired and brought aboard twins Chris Udvarnoky and Martin Udvarnoky.
The Other (1972) marked the feature film debut of noted stage actress Uta Hagen (1918-2004). The film also marked the only motion picture appearance of identical twins Chris Udvarnoky and Martin Udvarnoky, who appeared, respectively, as "Niles" and "Holland Perry."
The Other (1972) was shot entirely on location in Murphys, California and Angels Camp, California. Director Robert Mulligan had hoped to shoot the film on location in Connecticut, where it takes place, but because it was autumn when the film entered production (and therefore the color of the leaves would not reflect the height of summer, when the story takes place) this idea was dropped. Assistant director/associate producer Don Kranze picked the location for the house in Murphys, having remembered it from the film The Red House (1947). The fairground sequence was shot in Angels Camp.
Screenwriter Tom Tryon said he was deeply disappointed in the final result:
"Oh, no. That broke my heart. Jesus. That was very sad... That picture was ruined in the cutting and the casting. The boys were good, Uta was good, the other parts, I think, were carelessly cast in some instances --- not all, but in some instances. And, God knows, it was badly cut and faultily directed. Perhaps the whole thing was the rotten screenplay, I don't know. But I think it was a good screenplay."
In post-production, editing done to the film caused over half of Jerry Goldsmith's music to be left out. The soundtrack was finally available in 1997 along with The Mephisto Waltz (1971).