Factual error: When Alma and Whit drive along the coast, the road has recessed center line reflectors. These hadn't been invented yet in 1959 when the movie takes place.
Factual error: The opening scene is set in 1944, but the pickup truck in the background is from the late 1950s.
Factual error: Hitchcock is shown reading a newspaper with the headline "KING SPEAKS TO ALL BRITONS". But there was no King of England in 1959, Elizabeth II having succeeded her father in 1952.