Set in the year 1813 When Sharpe mentions the Spanish wearing grey Pat describes the Spanish as 'The Dons are always a bit gaudy'. The phrase gaudy was coined after Antoni Gaudi the architect who wasn't born until 1825.
During the final battle, when Kylie's soldier is looking at the "American" newspapers dated the previous day, Sharpe says, "The fastest clipper on earth couldn't cross the Atlantic in a day!" The term "clipper", in reference to a type of sailing vessel that sacrificed cargo capacity for extreme speed, didn't come into general usage for another twenty years or more.
Around 43m30s there is a crew member wearing a white shirt and blue shorts visible on the left hand side of the shot watching the fight scene.