During the scenes at Trafalgar, the main rudder of HMS Victory is shot, killing the pilot and one the helmsmen. At this point, Nelson orders to "engage the enemy more closely". These events are genuine, and happened exactly in the order depicted in the movie, according to HMS Victory's log.
After Glenda Jackson criticized her own performance in the film, calling it "rubbishy," Terence Rattigan pointedly suggested that she return her fee.
The postscript that appears at the end of the film reads, "Horatio, First Viscount Nelson, Duke of Bronte, was buried with full Naval Honours in St. Paul's Cathedral. Nelson's bequests were never carried out. As a result, Emma, Lady Hamilton, after two spells in debtor's prison, left England forever. She died in Calais on 15 January 1815, in abject poverty." The Encyclopedia Britannica article on Lady Hamilton says that she inherited money from both Lord Hamilton after his death in 1803, and from Lord Nelson after his 1805 death. But, "she squandered most of it, was imprisoned for debt (1813-14), an died in impecunious exile."
When Captain Hardy says "Sink me a ship, master gunner" this is a clear reference to The Revenge, Tennyson's poem about the Battle of Flores (1583). It is, however, an anachronism, as Tennyson wrote the poem 73 years after the Battle of Trafalgar.
Released in North America as The Nelson Affair.