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Just as he did with the play, John Patrick Shanley only told the actor who played Father Flynn whether or not Flynn was guilty. None of the other actors knew.
Philip Seymour Hoffman lobbied for Amy Adams to be a part of the movie even threatening to leave the project if she wasn't cast.
Oprah Winfrey reportedly lobbied for the role of Mrs. Miller, but John Patrick Shanley refused to even give her a reading.
Viola Davis, who was nominated for an Academy Award for her role as Mrs. Miller, only appears in two scenes. The first is an extended dialogue with Meryl Streep's character, Sister Aloysius. In the second, she appears only for about 10 seconds and does not speak.
The movie was dedicated to Sister Margaret McEntee, formerly known as Sister James, John Patrick Shanley's first-grade teacher.