Gibbs rule no. 20 Always look under.
When the HMS Shannon returned to England with the captured USS Chesapeake and its crew, the captain was buried with full military honours. Shortly afterwards the States had the body exhumed and returned home for burial. "No man left behind."
When Ducky says "our forefathers" built the USS Chesapeake, it is considered a mistake since Ducky is British, but the Chesapeake was designed by an Englishman and chances are it was built by Scots as there was a large Scottish immigrant population in America at the time of building.
The Royal Navy ship which captured the Chesapeake was called the Shannon, the same name as Gibbs's first wife.
This is the first episode featuring Robert Wagner not to be written by George Schenk and Frank Cardea.