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 movie, 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: Sir Alfred never re-mortgaged his house to help finance Psycho (1960)'s production. His wife Alma Reville never directed any scenes in the movie. His marriage was nowhere nearly as tumultuous as depicted. He never got involved during the production of the shower scene, and certainly never scared Janet Leigh.
In the end scene, a crow lands on Sir Alfred Hitchcock's shoulder, indicating that his next project will be The Birds (1963). That movie, and Sir Alfred's obsessive relationship with leading lady Tippi Hedren, were the basis for a television movie about him, The Girl (2012).
Many believe that real-life murderer Ed Gein inspired the character Norman Bates in the original Robert Bloch novel "Psycho", but this was not the case. Novelist Robert Bloch had already begun writing the book before the Gein murders were discovered. Once they had made the papers, however, the author noted the similarities between Bates and Gein. Gein was the inspiration for the character of Jame Gumb (Buffalo Bill) in Thomas Harris' novel "The Silence of the Lambs", which featured Sir Anthony Hopkins as Dr. Hannibal Lecter in the movie version. Michael Wincott, who played Gein in this movie, also played a similar killer in Along Came a Spider (2001).
Sir Alfred Hitchcock was offered Casino Royale (1967) to direct. It would have preceded Dr. No (1962) as the first James Bond movie 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
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.
When Sir Alfred 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 this movie 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.
Over the course of this movie, whether on purpose or not, Sir Alfred Hitchcock was 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 also had a difficult relationship with his mother, just as Norman did.
Alma Reville (Dame Helen Mirren) suggests to Sir Alfred Hitchcock (Sir Anthony Hopkins) that Marion Crane (Janet Leigh) be killed thirty minutes into Psycho (1960). Scarlett Johansson (Janet Leigh) first appeared thirty minutes into this movie.
When Alma (Dame Helen Mirren) visits Whitfield Cook's (Danny Huston'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.
A scene from The Secret Heart (1946), with Walter Pidgeon and Claudette Colbert, is playing on the television screen when Sir Alfred Hitchcock (Sir Anthony Hopkins) makes a derogatory comment about Whitfield Cook's (Danny Huston's) work.
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 movie.
Ralph Macchio portrayed Joseph Stefano in this movie. Macchio appeared on The Outer Limits (1995), season five, episode five, "The Other Side", an episode of the remake of The Outer Limits (1963), which Stefano produced and co-wrote.
In this movie, Anthony Perkins (James D'Arcy) said to Sir Alfred Hitchcock (Sir Anthony Hopkins) that he has seen his movies Rope (1948) and Strangers on a Train (1951) many times. Those two movies have often been interpreted to have gay innuendo between their male lead characters. Anthony Perkins was bisexual in real-life.
Sir Anthony Hopkins and Scarlett Johansson appeared in the Marvel Cinematic Universe. Hopkins played Odin in Thor (2011), Thor: The Dark World (2013), and Thor: Ragnarök (2017), and Johansson played Natasha Romanov/Black Widow. Though the two characters never meet, Johansson does have a scene opposite Loki (Tom Hiddleston), which closely resembles Hopkins' scenes with Jodie Foster in The Silence of the Lambs (1991).