When Hitch is being shaved, sometime after the North by Northwest premiere (8 July 1959), Peggy tells him that 20th Century Fox is offering him to direct The Diary of Anne Frank. "Diary" was already finished and premiered in March 1959, so such an offer would not have been made in that same year.
Dean Martin's recording of "Ain't that a Kick in the Head" plays when Janet Leigh meets the Hitchcocks prior to the start of filming. Filming on Psycho ended on February 1, 1960. The song wasn't recorded until May 10, 1960.
When Hitchcock arrives at the Paramount lot in 1959, water tower in background bears stylized studio logo not introduced until 1968, after the studio was acquired by Gulf and Western.
When Alma and Whit are driving up the Pacific Coast Highway, the double centerline is yellow. In 1960, it would have been white.
When Hitch is seated in front of his TV set watching a cartoon while listening to a classical record album, the piece that is heard, which is correctly credited, is the scherzo movement from Ludwig van Beethoven's 3rd Symphony (Eroica). However the record album cover that is on top of the TV-stereo console is entitled "Beethoven Overtures."
Hitchcock addresses the film music composer as "Bernie." Virtually no one called Bernard Herrmann that; those who were close to him called him "Benny."
While Hitch is in the middle of a chapter of "Psycho", Alma takes the book from him. He takes it back but continues reading from the beginning of another chapter.
When Hitch is finished being shaved in the barber's chair we see shaving cream residue on his cheeks. When he looks at his reflection in the hand mirror, the residue is gone, but when we see him from the front again, the residue is back.
Portrays principal photography and Alfred Hitchcock's office as being on Paramount Studios' backlot. In reality, as Psycho was the last picture the director would make under his contract with Paramount, by the time filming began his office, as well as the sets, had moved to his new studio, Universal.
In the on-set scene in which Arbogast (Martin Balsam in the original Psycho) is about to be stabbed, Anthony Perkins' character is seen sitting nearby in drag as Norman-as-Mrs.-Bates. In reality, Anthony Perkins was not even on set this day (Alfred Hitchcock used a female "little person" as a double so audiences wouldn't be tipped off to the murderer's true identity by Perkins' height.) In fact, the only time Perkins actually appeared onscreen as Mrs. Bates was during the big-reveal climax in the fruit-cellar. Doubles and stand-ins were also used during the shower murder for reasons of convenience and deception.
The film presents several erroneous facts about real life killer Ed Gein:
1. The film opens with Ed Gein killing his brother,Henry with a shovel in 1944; actually, the police investigated Henry Gein's death at the time and found no evidence of foul play- and the official coroner's report states that Henry Gein died of asphyxiation while fighting a fire on his property. While many authors have suggested that Ed murdered his brother (especially after the revelations of Ed's later activities) this has never been proven.
2. At one point, when talking to his secretary, Hitchcock (Anthony Hopkins) refers to Ed Gein as "the mass murderer from Wisconsin". In reality, there were only two confirmed murder victims of Ed Gein, which, although terrible, hardly constitutes a "mass".
Finally, in the same conversation, Hitchcock refers to Gein as "the boy who dug up his own mother". Although Ed Gein was a proven grave robber- which was and is a terrible crime- there is nothing in historical records of his crimes mentioning- or even suggesting- that he exhumed his own mother's remains.
At two occasions we see the famous Bates Mansion in the background, facing the right side of the house, opposite of how it appears in Psycho. Originally the house was constructed with only 2 walls - the left and front facade.
As Alfred Hitchcock is reading the London Times over his breakfast you can clearly see a news report of "The King Speaks to all Britons". Great Britain has had Elizabeth II as monarch since 1952.
Hitchcock talks about a quote from the New York Times and says there is an "accompanying list", but the paper he is reading which contains that list is clearly The Times, aka the London Times.
When Hitch is in the meeting with the censors, the stenographer is clearly faking the keystrokes.