When Emma and her mother first meet Sir William and the French ambassador; her hand and purse change orientation from shot to shot.
When Nelson is dying the orientation of Hardy's arm changes from one shot to another.
During the battle of Trafalgar, a ship with four gun decks is shown burning and sinking. This can only be the Spanish ship Santísima Trinidad, the only ship in the battle with four gun decks, and the largest and most powerful 'battleship' in the world at the time. The real Santísima Trinidad was captured by the British and taken in tow as a war prize, but was lost in a storm at sea on its way to England.
When Captain Hardy tells Lady Hamilton about Nelson's death, nearly all the details of the combat are wrong. Hardy says they were fighting the French flagship Redoutable, after approaching under heavy fog. He also says Nelson died at sunset. Actually, the French flagship was the Bucentaure, not the Redoutable, and the heavy fog had cleared since the morning. Also, Nelson was pronounced dead by 16:30, not sunset. Moreover, during the battle scenes, several ships can be seen exploding. In reality, only one ship, the French 74 gunner Achilles, blew up.
In 1798, Nelson was in the White squadron and so would not have been made Rear-admiral of the Blue. In fact, the highest rank he attained was Vice-Admiral of the White.
The ship Nelson commands when he arrives in Naples, HMS Agamemnon, is depicted as a three decked ship of the line (a 'battleship' as Emma calls it). HMS Agamemnon was actually a third rate ship of the line, and only had two gun decks.
Nelson never wore an eye patch, as depicted in this movie.
The smoke cloud above the Vesuvius volcano that is seen from the balcony of Lord Hamilton's Naples palace never changes. From scene to scene, year to year, the plume remains the same: an inverted cone of smoke with another inverted cone of smoke rising from it to the right.
After the rowboat picks up Lord Nelson who was on the pier with Emma; the coxswain barks out the order, Starboard and Back Starboard. However all the oarsmen both Port and Starboard place their oars down in the water. Only the men on the Starboard side (right side) were supposed to put the oars in the water.
The opening footage of Lady Hamilton and guests in the balcony during the concert is used twice. Once before the shot of the King humming and again after the shot of the soldiers watching the concert.
The UK had no formal registrations of births prior to 1837. The only records were those of baptisms at parish churches.
At a victory party for Nelson in 1798, a band plays "A Life on the Ocean Wave," the Royal Marines March written by Henry Russell in the 1830's.
When Lord Nelson dies Hardy then starts to shut Nelson's eyes starting with the left eye. However, while Hardy is shutting Nelson's left eye; Nelson simultaneously closes his right eye out of his own volition. Hardy then acts as if he is closing the right eye despite the fact that it is closed already.