Alfred Hitchcock is shown directing a scene for "The Birds" on location wearing a bowler hat whilst seated in his director's chair. Hitchcock was photographed wearing a bowler (for publicity purposes) whilst making "Frenzy" in autumnal London nearly a decade later, and wears one in his brief personal cameo in that film. In reality, however, he never wore headgear (and wearing a hat on a windy day whilst near the sea would surely have been foolish).
In this film, Alfred Hitchcock is seen proposing a toast to "Alfie and Tippi". In reality, Hitchcock never called himself "Alfie", and never liked to be called either "Alfie" or "Alfred"; he was always called "Hitch", at his own insistence.
California license plates are incorrect format; the "56" should be after "California", for passenger cars the numbering should be three letters+three numbers; also the font is incorrect. In addition, during the filming of Marnie (after May 1963), the color changed from the 1956 black letters on yellow plates to 1963 yellow letters on black plates. The number system was still three letters+three numbers until 1970.
In every scene where there are telephones, British GPO 700-series phones are seen. In the area where Universal Studios is located Western Electric 500-series phones were used (or earlier) because it is in Pacific Telephone and Telegraph Company territory (now AT&T).
In one scene, Hitchcock and the screenwriter of 'Marnie' conduct a conversation in the back of a car en route to the studio. In external shots, the car is seen driving on the right (on temporarily closed roads) but in internal shots the car is driving on the left. The film was made in South Africa, where cars drive on the left.