Captain Pellew's line, "As idle as a painted ship upon a painted ocean," is a quotation from the second part of 'The Rime of the Ancient Mariner' by Coleridge. It was first published, anonymously, in 1798.
The guillotine used for the execution scenes was designed, built and supervised by a local Portuguese magician.
Major Edrington states he is with the 95th regiment of foot. This was a real regiment that was raised in 1793 under Major-General Edmeston, and disbanded in 1796. In 1800 the next foot regiment to be termed 95th was originally formed as a Corps of Riflemen (also known as the Rifle Corps) by detachments from various regiments, before being numbered the 95th (Rifle) Regiment in 1802. It was this regiment that Richard Sharpe of the Bernard Cornwall novels and tv show was drawn from. In 1816 the regiment was renamed the Rifle Brigade.
In the original novel Mr. Midshipman Hornblower, "The Frogs and the Lobsters" occurs before Hornblower receives his promotion to Lieutenant, or even being ranked Acting-Lieutenant. Furthermore, the novel does not have any love interest for Hornblower.
In the original Hornblower novels, when Hornblower is commissioned a lieutenant he is transferred from Pellew's command to serve on the HMS Marguerite, commanded by a brutal captain who frequently flogs and abuses the crew. Hornblower immediately becomes an advocate for the sailors and eventually talks them out of starting a mutiny. When the Captain still attempts to punish a large group of seaman, Hornblower has them transferred as a prize crew to get them out of the Captain's grasp. It is only then that Hornblower transfers back to Pellew's command, with the experience onboard the HMS Marguerite explaining Hornblower's later compassion for the men under his command. None of these backstory details are in the television series, which shows Hornblower as a new lieutenant remaining onboard Pellew's ship.