Richard H. Thorndike is hesitant to reveal his middle name (Harpo) to Madeline Kahn. In Alfred Hitchcock's North by Northwest (1959), Cary Grant's Roger O. Thornhill never reveals his middle name.
This tribute to Alfred Hitchcock contains references to more than 10 of his films: see the links to other titles. Mel Brooks held a private preview of the movie for Hitchcock to see his reaction. When Hitchcock walked out at movie's end without saying a word, Brooks feared that Hitchcock hated the movie. But days later, Hitchcock sent a congratulatory case of wine to Brooks, knowing that Brooks was a wine connoisseur.
In the shower scene, the showerhead adjustment knob projects straight up out of the top of the showerhead when viewed from outside the shower, but is turned sideways when viewed from inside the shower.
When the huge threatening note comes though the bathroom windows attached to a boulder, the lid of the toilet tank is knocked into a diagonal position. In close-up shots the tank lid is askew, but in long shots the tank lid is undisturbed.