Doing It for the Art: Hitchcock went to a lot of trouble to try and avoid the film's twists being revealed. Most notably, he went about buying up copies of the source novel out of his own pocket.
Look closely after the psychiatrist scene, when the cop takes the blanket to Norman. See the other, non-speaking cop who's standing guard outside the door? It's a young Ted Baxter!
Real-Life Relative: The brief appearance by young Norman in Psycho II was Anthony Perkin's son, Oz.
Throw It In: Location shooting (for the scene where Marion drives out of town with the money) was done in downtown Phoenix in December 1959. After Christmas decorations were discovered to be visible in the footage, a graphic was added to the beginning of the film setting the date as "Friday, December the Eleventh".
Also, Norman's Character Tic of eating candy was a suggestion of Perkins's that Hitchcock happened to like
What Could Have Been: Hitchcock originally wanted the shower scene to play without music, but Herrmann begged him to try it. Yes, the Trope Maker for Psycho Strings very nearly didn't come about at all.
