At the beginning of the film, when Steve goes through the door from his office into the boardroom, the view looking back into his office from the boardroom is nothing like the office he just left. There are pictures where a large window should be. And, view out of the boardroom window is completely different than the view out of Steve's office window - which is right next door.
When Cagney rings doorbell on his first visit to Stanwyck's house, the bell rings before he actually presses the button.