Real-life murderer Ed Gein inspired the character Norman Bates in the original Robert Bloch novel 'Psycho'; Gein also inspired the character of Jame Gumb (Buffalo Bill) in 'Thomas Harris''s novel 'The Silence of the Lambs' which featured Anthony Hopkins in the film version.
In the end scene, a crow lands on Hitch's shoulder, indicating that his next project will be The Birds (1963). That film, and his relationship/obsession with leading lady Tippi Hedren were the basis for another film about Hitchcock, The Girl (2012), broadcast this same year.
When Hitchcock is being driven home by Janet Leigh, when she questions his eating of the candy corn (which is not as posh and refined as his usual taste), he says "needs must when the devil drives". This is an old British phrase used in several Shakespeare plays that means when one is in a desperate situation, one must do things they don't normally do. This line and scene are meant to imply that he is agitated and his mental state is not what it normally is.