This is the first film in which a person's thoughts are presented on the soundtrack.
The scene where Sir John thinks out loud in front of a mirror had to be filmed with a recording of the lines and a thirty piece orchestra hidden behind the set, as it was not possible to post-dub the soundtrack later.
A German version called Mary (1931) was filmed at the same time using German actors but the same sets.
The character of Sir John Menier (Herbert Marshall) was loosely based on Sir Alfred Hitchcock's friend Gerald du Maurier. Hitchcock later directed three films adapted from novels by du Maurier's daughter Daphne Du Maurier: Jamaica Inn (1939), Rebecca (1940) and The Birds (1963).
The film takes place from April to May 1930.
Alfred Hitchcock: About an hour into the movie, walking past the house where the murder was committed.