(around 55 mins) When Steve Sanky is walking toward Mrs. Anna Maurant's building, he passes a man in a suit walking in the opposite direction and carrying an article of clothing. However, when it cuts to the next shot which is from the reverse angle, you see Sanky passing the same man again.
When the milkman arrives in the morning, a moving shadow of the boom microphone is visible to the right of the stoop and is seen again a moment later when Sam comes out of the building.