Factual error: In the post office scene, Susan's letter has stamps totalling 16 cents. First class was only three cents in 1947.
Factual error: After the credits, at the beginning it shows "New York 1883" but in an early scene when Powell is reading the newspaper in his study he is complaining about the Mayor of New York whom he calls "Honest Hugh Grant." Hugh J. Grant did not become mayor until 1889.