There's a scene when Barbara Stanwyck hides behind an open door to avoid beeing seen by Edward G.Robinson leaving Fred MacMurray`s apartment. To make this possible the apartment door opens outside into the corridor, which is an elegant solution for this situation in the movie. But in the real world no apartment door would open by swinging into the corridor because this would give a visitor standing there a punch on the nose when the resident opens the door.
Fred MacMurray wears his real-life wedding ring throughout the movie. His character in the movie is single.