In the attic scene in The Birds, Hitchcock had crew guys hurling real gulls and crows at Tippi Hedren...for five straight days of shooting. As a result, she was plagued by dreams of flapping wings. The birds themselves had been fed whiskey to make them more aggressive. Needless to say, this was long before the No Animals Were Harmed certificates.
The story of Rebecca called for Joan Fontaine to be nervous around the other actors, so Hitchcock told her that no one else on set liked her. Laurence Olivier did hate her, repeatedly telling Hitch, "She can't act, old boy!". This was more because of Joan Fontaine's inexperience at the time than anything else. For Suspicion, for which she won an Oscar for Best Actress, he relied on her more. Fontaine enjoyed working with Hitchcock on the whole.
For Vertigo, Kim Novak was not his first choice, and most of the costumes were selected for Vera Miles (she appeared in The Wrong Man and played Marion Crane's sister later in Psycho). So Kim Novak's stiffness and discomfort as Madeleine emphasized by costumes for another actress actually helped her in that role.
Hitchcock was a notorious practical joker and was never tired of making jokes and shocking his cast and crew. When filming The 39 Steps he needed a shocked reaction from Madeline Carroll. He achieved this by pretending to pull his cock out.
Hitchcock's first film, a 1923 release called The White Shadow, was thought lost for more than 80 years—until its first three reels were found as part of a private collection in New Zealand.
1927's The Mountain Eagle is not known to survive in any form, despite exhaustive searches of film archives. Check your attic. In his interviews with Truffaut, Hitchcock was dismissive of the film, insisting that it was not a very good film and that the succeeding film, The Lodger was his first major work.
Several of the actors had Undying Loyalty to Hitchcock. A prime example of this is actor Norman Lloyd, who later went on to play Dr. Daniel Auschlander on St. Elsewhere and Dr. Isaac Mentnor on Seven Days, who worked for Hitchcock as an associate producer and director on Alfred Hitchcock Presents. At the time, Hitchcock was the only person willing to give him any type of gainful employment. Other than that, he had been blacklisted in the entertainment industry for refusing to testify before the House Un-American Activities Committee and identify suspected communists and as a result, had been branded as a communist himself.
Screenwriter Angus Mac Phail (who he credited for coining the McGuffin) had trouble with alcoholism and Hitchcock arranged him to work on The Wrong Man to help his friend out.