The date the story takes place is given as 24 June 1973.
Second and final appearance of James Doohan as Lawrence Tobin. Doohan was later offered the regular role of Chief Francis Sharkey, but turned it down in favor of playing Montgomery Scott in Star Trek (1966), which became his most famous role.
The title makes reference to the march "Hail to the Chief" which announces the entrance of the President of the United States at public appearances and is preceded by four ruffles and flourishes. Believed to be based on a Scottish melody, it has been played for Presidents since the 1820s. The march is often played by the United States Marine Band and has been used officially by the Department of Defense since 1954.
The President's name is Henry Talbot McNeal. It can be logically presumed that this is the same President played by Ford Rainey in Hot Line (1964) before this one and Doomsday (1965) afterward. However, in this one Rainey is substituted by an uncredited stand-in who does not speak.
One of the few television programs or movies where "Norfolk" is pronounced properly like the natives or military personnel who have been stationed there. Most of the time, actors or announcers mis-pronounce it as "Nor-FOLK".