In his interview with François Truffaut on "Shadow" (first published in 1967), Sir Alfred Hitchcock said the dense, black smoke belching from the train that brings Charles Oakley to Santa Rosa was a deliberate symbol of imminent evil.
Teresa Wright did not read the script before agreeing to sign on for this movie. Sir Alfred Hitchcock described the plot to her in a meeting, and she agreed to take on the part immediately.
Sir Alfred Hitchcock said that part of why he considered this to be his favorite movie was that he loved the idea of bringing menace to an otherwise idyllic small town.
Edna May Wonacott (Ann Newton) and Estelle Jewell (Catherine) were locals of Santa Rosa, where this movie was shot on location. Many of the extras were also residents of the town, which was too far away from Hollywood to be affected by Actors Guild guidelines demanding the use of professional actors and actresses.
Alfred Hitchcock: On the train to Santa Rosa, California playing cards. He has the entire suit of spades in his hand, including the symbolic Ace. Being the director, he was "holding all the cards".