At the end of the episode Captain Montgomery presents Castle a bottle of whisky with both hands. Castle accepts the whisky and says that he want to share it. Captain Montgomery eagerly presents a glass to get his share of the whisky. The glass seems to have appeared from thin air as it was not in his hands when Captain Montgomery gave the whisky to Castle.
When Becket and Castle are looking at plat/sewer maps, Becket points to where the mystery man got away. Next to that, the map clearly shows The Banning Museum. The Banning Museum is in the Wilmington district of Los Angeles, not lower Manhattan. Either the show used real plat maps of L.A. (unlikely) or they made there own and added this intentionally.