A significant plot element of this episode is that it took Harm two years to realize that Agent Turque was stationed aboard Diane's ship. But when they first meet in the flashbacks, Agent Turque clearly introduces himself to Harm as an "NCIS agent aboard the Seahawk."
While Harm waits on a pier to intercept the XO, eventually the ship's bell strikes eight bells to mark the time of 04:00 and the end of the mid watch. However, a landlubber, not a mariner, strikes the bell with evenly spaced single strokes, whereas, in the real world of the US Navy, the bell is struck with pairs of strokes. Besides, the ship's bell does not sound the time during the night between lights-out and reveille.
Bud tells Mac that Agent Turque had not been on board the Seahawk during the cruise prior to Diane's death. In the archive footage of the crime scene, Agent Turque introduces himself to Harm and Meg as the NCIS afloat.