When Monk is playing the card game on the street, you can see the show's creator/writer Andy Breckman standing behind him as a spectator.
When Mr. Monk and the Captain are talking on the street opposite Radio City, the workman with the jackhammer is looking for his cue to start the jackhammer every time Monk speaks.
Ted Levine and Mykelti Williamson also played police officers working together in the movie Heat (1995).
When Mr. Monk and the Captain are talking on the street next to a man with a jackhammer, they are across the street from Radio City Music Hall. The event being promoted was "An Evening With Josh Groban" and the words "Sold Out" to the far right. Radio City Music Hall was one of 40 planned stops on Josh Groban's first tour as a headliner. The concert at Radio City Music Hall was the only multi-night stop on that tour that began in Boise (1/22) and ended in Miami (4/23)