In the beginning when the Anvil Salesman gets on the train, he sits down, arms to the side, the camera angle changes, and his arms are immediately on his hat adjusting it.
Shirley Jones was pregnant during the movie. She wore a special corset to conceal this. Director Morton DaCosta did not want anyone else involved in the movie to be aware of her pregnancy. He was so successful, that it was not until the kissing scene on the bridge that Robert Preston (Harold Hill) found out, when he was shocked to feel Jones' baby kicking him in the stomach.