Nell Potts, who plays Rachel as a young girl, is actually Joanne Woodward and Paul Newman's daughter.
The production was a small-scale one, with a small budget (reportedly only $700,000) but it eventually emerged as quite a big moneymaker, as well as being one of the studio's prestige movies of its year.
The uncredited baby on the beach with Rachel at the end of the film is Claire Newman, then age 2, whose face is never shown because she was crying throughout most of the scene; the waves lapping against the shore scared her, as she didn't yet know how to swim.