When John Wayne first meets with the woman at the church, the first time we see her she puts a dark piece of clothing over her head. In the next scene, which is a closer angle, it is gone.
Many of the actors in this film were related. Barry Fitzgerald and Arthur Shield were brothers. Charles and James Fitzsimons were Maureen O'Hara's real-life brothers (Fitzsimons was her real surname), and Francis Ford was director John Ford's brother.