By far the biggest piece of irony in this whole tale comes at the very end. Remember, work-obsessed Tom Benecke has gone out onto the ledge to retrieve a very important piece of paper that he needs for his work. To focus on his work he has let his beautiful wife go out by herself to the cinema. It is clear that things have changed for Tom during his outdoor escapade and his near-death experience, as is shown by the end paragraph:
There he got out his topcoat and hat and, without waiting to put them on, opened the front door and stepped out, to go find his wife. he turned to pull the door closed and warm air from the hall rushed through the narrow opening again. As he saw the yellow paper, the pencil flying, scooped off the desk and, unimpeded by the glassless window, sail out into the night and out of his life, Tom Benecke burst into laughter and then closed the door behind him.
This is a very clever piece of situational irony, as the note that Tom has gone through so much to rescue and has risked his life for is now lost again, through the same window, but this time Tom laughs, completely welcoming its departure from his life, and walks out of the door to join his wife. He has clearly learnt where his priorities should be - and they should not be with work alone.