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.
As the film needed to take place during summer, the small town of Murphys, California, substituted for a location in Connecticut.
This is the only screen credit of twins Chris and Martin Udvarnoky.
Screenwriter Thomas 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).