At one point a sailor is heard singing "Oh Shenandoah." While the origins of this folk song remain unclear, most believe it originated in the early 1800s and thus would not have been known at the time of this movie's 1797 setting.
In the last scene, Alec Guinness orders all larboard (left side) guns to bear on the fire ship. In the next shot, the starboard (right side) cannon fire. Ironically, the term "larboard" was changed by the navy into the current term "port" precisely because it was too easy to mistake it for starboard.