She appeared in only one film, "The Bad Seed", in which she reprised her stage role, Miss Fern. It was rather surprising casting, given that Croydon was a quite lovely young woman at the time, and the character she played, a murderous child's suspicious teacher, is one described in the play's stage notes as "dowdy", "a spinster", and "middle aged", and is generally played by much older actresses. In any event, Croydon received a poor review for her film performance from the "New York Times"' film critic, Bosley Crowther, who gave poor or mixed reviews to the entire cast in his review.