Per Sir Alfred Hitchcock's instructions, Dame Judith Anderson rarely blinks her eyes while playing Mrs. Danvers.
Over 20 actresses were screen-tested for the role of Mrs. de Winter, which eventually went to newcomer Joan Fontaine. One of them was Vivien Leigh, for whom Sir Laurence Olivier was pressing, as they were a couple at the time.
Mrs. Danvers is hardly ever seen walking, she seems to glide. Sir Alfred Hitchcock wanted her to be seen solely from Joan Fontaine's character's anxious point of view, and this effect tied in with her fear about Mrs. Danvers appearing anytime unexpectedly.
Due to the success of this movie in Spain, the specific jackets that Joan Fontaine wore during the movie began to be known as "rebecas". The word "rebeca" is still used nowadays to refer to this item of clothing.
For the only time in his career, Sir Alfred Hitchcock was barred from the scripting process. Therefore, he banned producer David O. Selznick from his own set.
Alfred Hitchcock: Walking past a phone booth just after Jack Favell (George Sanders) makes a call in the final part of the movie. There are photos showing Hitchcock standing beside the phone booth looking at Mr. Sanders. Actually, the scene isn't played that way, and you have to be quick spotting Hitchcock, quickly passing by in the background while Sanders is discussing a parking matter with a policeman, with Sanders having only been seen in close up while talking on the phone.