Dame Helen Mirren, who plays Hitchcock's wife Alma Reville, had also met the real Sir Alfred Hitchcock when he approached her for a part as a murder victim in his penultimate film, Frenzy (1972). Mirren turned down the role, a decision she later regretted.
Sir Alfred Hitchcock biographer, Patrick McGilligan, noted several fictions created by the movie for artistic reasons. These included that in real-life: Hitchcock never re-mortgaged his house to help finance Psycho (1960)'s production. Hitchcock's wife Alma Reville never directed any scenes in the movie. Hitchcock's marriage was nowhere near as tumultuous as depicted. Hitchcock never got involved during the production of the shower scene, and certainly never scared Janet Leigh.
Hitchcock was offered Casino Royale (1967) to direct. It would have preceded Dr. No (1962) as the first James Bond film by two years, if it had been made at that time. Casino Royale's screen rights were sold separately from the other Ian Flemimg classics. It was first made into a television drama with Barry Nelson, and later Charles K. Feldman produced the first screen version in 1967 as a satire, with Peter Sellers, David Niven, and Woody Allen
When Hitchcock (Sir Anthony Hopkins) is being driven home by Janet Leigh (Scarlett Johansson), 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 William 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.
Although many reviewers criticized the film for inventing an intimate relationship between Alma Reville and Whitfield Cook, the facts are documented by more than one Hitchcock scholar, as exemplified by Patrick McGilligan, in his biography of Sir Alfred Hitchcock. That writer accessed Cook's private diaries, available in Cook's papers donated to the Howard Gotlieb Archival Research Center, Boston, Massachusetts.
When Alma visits Whitfield Cook's beach house, they start to work on a book called "Taxi to Dubrovnik". This book is real, and it was published by Cook in 1981. It is about three vacationing Americans who travel by hired car from Athens, Greece to Dubrovnik, Yugoslavia.
During an early planning scene, Alma Reville suggests that her husband kill off Marion Crane after thirty minutes. In Psycho (1960), Mother first appears in the shadows at 48:10, then kills Marion, who collapses at 49:20, just under halfway through the film.
The trivia items below may give away important plot points.
In the end scene, a crow lands on Hitchcock's shoulder, indicating that his next project will be The Birds (1963). That film, and Sir Alfred Hitchcock's obsessive relationship with leading lady Tippi Hedren, were the basis for a television film about Hitchcock, The Girl (2012).
Over the course of the movie, whether on purpose or not, Hitchcock is subtly starting to take over habits from Norman Bates. For example, he accepts candy corn from Janet (which Norman habitually eats in Psycho (1960)), and at one point, he is listening to Ludwig van Beethoven's Third Symphony ("Eroica") in his house (which Norman had on his record player). Although not addressed in the movie, Sir Alfred Hitchcock also had a difficult relation with his mother, just as Norman did.
A director's chair with the words "Mrs. Bates" can be seen in the background. The chair can be seen in publicity shots with Hitchcock sitting in it. Mrs. Bates doesn't appear in Psycho (1960) in an alive state.