Defictionalization: C. Northcote Parkinson (he of Parkinson's Law) wrote a thick, thoroughly researched and realistic biography of Hornblower that could easily be mistaken for being about a real naval hero. Complete with portraits, maps, a family tree, and some plausible extrapolations. For example, Hornblower's first name was really Horace, and a letter released a century after his death reveals he really did kill Captain Sawyer.
Reality Subtext: Commodore was less historically-researched than the others. Instead, it reflects World War II: Russia's tenuous alliance with England and threat from invaders, occupied and/or neutral Baltic/Scandanavian powers, and Britain's tenuous support.
Recycled Script: The 1940 short story "Hand of Destiny" reads like a rough blueprint for Lieutenant Hornblower: junior lieutenant Hornblower must cope with a tyrannical captain, there is mutiny, a victorious action against a Spanish target distracts from the toxic atmosphere, the captain is removed from the picture in a way only Hornblower ever knows, and he ends the story promoted. The differences are that Captain Courtenay is explicitly not mad, just cruel, he's disabled rather than killed, and we know who did it since it's from Hornblower's point of view (in this case he saw the man take aim and chose not to intervene or tell anyone), and he goes from junior to first lieutenant rather than a full jump in rank.
Horatio, 17 years old as of the first film, was played by 25-year-old Ioan Gruffudd.
Same with the then-25 year old Jamie Bamber as 17-year old Archie Kennedy.
Doing It for the Art: The first series was filmed on ships, and it looked awesome. The second series wasn't; but it still looked pretty good. Sadly averted with the third series, which was done carelessly, and it shows, especially compared to the previous cool instalments.
Executive Meddling: The Forrester estate would only let "Mutiny" and "Retribution" film if Archie Kennedy was written out. (Not unreasonably, since his friendship with Horatio was changing Horatio's characterization too drastically from the source.) The writers convinced them to at least let him die on screen. They then pulled a fast one and had Archie perform a Heroic Sacrifice to save Horatio. And the estate couldn't do anything about it. It could also be argued as a case of Be Careful What You Wish For: they got the dour Horatio of the books, but fans (those that don't ignore Archie's death, anyway) interpret that as a result of the circumstances of Archie's death, rather than a part of his personality.
Fake American: The Irish/English actress Camilla Power as American Betsy Bonaparte.
Fan Community Nickname: Archie's fans call themselves Crumpeteers. note It originated at A&E message board "A Naughty Pellew Fantasy". The nickname then appeared in a piece of fan fic "All About Major E." AKA "All About Lord Edrington" by Karen (AKA SeaSpotRun). It was a tongue-in-cheek questionnaire filled in by Major Edrington who called Archie "a panicky bit of Blonde Crumpet".
Keep Circulating the Tapes: A&E Network/Meridian never released the show's epic music score, no matter how badly fans begged for it. The best fans can do is to rip the sound from DVDs. There are files to be found on line, but there are some background noises...
Sending Stuff to Save the Show: Hornblower fans (mostly fan girls) organize postcard drives from time to time. Unfortunately to no success, but hope never dies.
Weapons Understudies: The HMS Indefatigable, a 44 gun heavy frigate razéed from a 64 gun ship of the line due to that class' obsolescence, mounting heavier guns and thicker hull than normal, is portrayed by the Grand Turk, a replica of the 20 gun post ship HMS Blandford, which only mounts ten guns, six nine pounders and four 6 pounders. In "The Even Chance", it (more accurately) doubles as the corvette Papillon, which somehow sinks the 74 gun Justinian, despite not mounting guns that could even dent her hull.
What Could Have Been: Paul McGann was cast in the adaptation of Sharpe, but he broke his leg and the role was re-cast. If that hadn't happened, he would have been shooting Sharpe and Mr Bush would have been portrayed by somebody else.
Word of St. Paul: According to Jamie Bamber, Archie is the third son of Scottish lord. Given his status as a Composite Character, the majority of his backstory is composed of either the actors' and writers' statements about him, or Fanon.