Mr. Monk Takes Manhattan - S3-E1
Deliberate mistake: After Monk and Sharona speak to Gratnik in Dumbo, they take the subway back to Manhattan. While Monk is sobbing, in the first exterior shot the "A" train slows into the 42 St station in Manhattan; note the "A" at the left with the driver on the right, as well as the "42" station sign not reflected backwards, all revealing a flipped shot. Then it's the "C" train when it stops, with Monk and Sharona back in Brooklyn, even further now at the "Hoyt-Schermerhorn Street" platform (used for TV shows and films), in lower Downtown Brooklyn. (00:21:55)
Answer: The two men are trying to work out a secret deal between them without involving the union, which means the workers' interests aren't being represented and defeats the whole purpose of a union. The mayor would lose labor's support and Cusack's union troubles would just be starting.
Captain Defenestrator