Veronica Cartwright (Rosalie) said in an interview that she and the other children were told not to hang around with Shirley MacLaine on set because she "cursed a lot". They all did, however, because they thought she was "cool" and "very generous". She also became Cartwright's mentor throughout the making of the film.
The original stage-play was partly inspired by an actual case in Edinburgh, Scotland in 1810. A pupil named Jane Cumming accused her schoolmistresses, Jane Pirie and Marianne Woods, of having an affair. Dame Cumming Gordon, the accuser's influential grandmother, advised her friends to remove their daughters from the boarding school. Within days the school was deserted and the two women had lost their livelihood. Pirie and Woods sued and eventually won, both in court and on appeal, but given the damage done to their lives, their victory was considered hollow.
William Wyler cut several scenes hinting at Martha's homosexuality for fear of not receiving the seal of approval from the Motion Picture Production Code. At the time, any story about homosexuality was forbidden by the production code.
The start of the movie implies that Mary gets the idea to "accuse" Karen and Martha of lesbianism from a forbidden book that gets passed around secretly among the school's students. Although this book is not identified by title in the movie, Hellman's play specifies that the book is Mademoiselle de Maupin by Théophile Gautier, a French novel published in 1835. The novel concerns a woman who disguises herself as a man and has both a woman and a man fall in love with her, so it did contain at least the concept of lesbianism and therefore answers the question of how Mary could have conceived of the charge she levels against Martha and Karen without ever actually seeing them engage in any romantic or sexual activity.
Shirley MacLaine, in the documentary The Celluloid Closet (1995), said that nobody on the set of The Children's Hour (1961) discussed the ramifications of the issues regarding homosexuality that are implied, but never spoken about outright, in the film. She said, "none of us were really aware. We might have been forerunners, but we weren't really, because we didn't do the picture right. We were in the mindset of not understanding what we were basically doing. These days, there would be a tremendous outcry, as well there should be. Why would Martha break down and say, 'Oh my god, what's wrong with me, I'm so polluted, I've ruined you.' She would fight! She would fight for her budding preference. And when you look at it, to have Martha play that scene - and no one questioned it - what that meant, or what the alternatives could have been underneath the dialog, it's mind boggling. The profundity of this subject was not in the lexicon of our rehearsal period. Audrey and I never talked about this. Isn't that amazing. Truly amazing."
Miriam Hopkins who played Martha in the original film These Three (1936) played the part of Martha's Aunt Lily. Merle Oberon, who played Karen in the original film, turned down the part of Mrs. Tilford.
Screenwriter John Michael Hayes was so faithful to Lillian Hellman's play that much of the dialogue is identical to the dialogue in These Three (1936), the 1936 film version of The Children's Hour, for which Lillian Hellman herself wrote the adaptation and screenplay - this, despite the fact that These Three (1936) was a watered-down, censored version of The Children's Hour.
Re-titled "The Loudest Whisper" for UK release to avoid confusion with the BBC's popular "Children's Hour" slot on radio and TV.
Program notes on back of both of US VHS and DVD editions claim that Katharine Hepburn was sought for one of lead roles that eventually went to Audrey Hepburn and Shirley MacLaine, both of whom played teachers newly-graduated from college. By the early Sixties, Hepburn was far too old for either role and, if ever actually considered for a part in the movie, would have been suitable only for far more mature roles played by Miriam Hopkins or, more likely, Fay Bainter.
The Broadway production of "The Children's Hour" by Lillian Hellman opened at the Maxine Elliott's Theatre on November 20, 1934 and ran for 691 performances.
Audrey Hepburn had a dog named "Mr. Famous" that she would bring to the studio while she was making this film. Mr. Famous got out of her trailer one day for about an hour and Audrey had the studio police looking for him. They eventually found him on top of a wall that he had somehow managed to climb.
Cathleen Nesbitt was originally announced to play the grandmother role that went to Fay Bainter.
Both Katharine Hepburn and Doris Day were originally offered the lead roles that went to Audrey Hepburn (no relation) and Shirley MacLaine.
"The Children's Hour," which William Wyler directed, had a cast that included two actresses who had won Oscars under his direction: Audrey Hepburn (Best Actress, "Roman Holiday," 1953) and Fay Bainter (Best Supporting Actress, "Jezebel," 1938). Bainter was nominated for her supporting performance in this movie, but she lost to Rita Moreno ("West Side Story").