Factual error: This episode begins with a luxury cruiser being pursued by a USN Oliver Hazard Perry class frigate. In order to convince the vessel to heave to, the skipper of the USN ship orders two warning shots to be fired from the frigates forward gun. Oliver Hazard Perry class frigates do not have a forward gun. They have a launcher, which is visible in the ships external shots. The shot of the 5" gun firing is archive footage of a completely different (and much larger) vessel.
Factual error: The coast guard officer on the bridge in the opening scenes is wearing the gold oak leaves of a LCDR but the gold trim on his hat indicates he is a full commander. Later in the episode he is identified as a full commander but is not called Sir by Harm or Mac. In reality, as a senior member of a US uniformed service, he would be called Sir.
Factual error: In this episode there is continual reference to the seahawk helicopter in the hanger. The helo that is pictured in the episode is a lot bigger than a seahawk and resembles a sea king. Oliver Hazard Perry class frigates can hold two seahawks but no Sea Kings.
Answer: Officially, the individual has been ordered to attend, failing to could be interpreted as either, Failure to follow orders, dereliction of duty, going AWOL, or even desertion. It would depend on the underlying reason as to why the person doesn't appear.