Factual error: In the ambush-on-the-prison scene, one of the Boers is equipped with a Lee-Enfield CLLE Charger-Loading Rifle. Although the Boers used many captured Lee-Enfield and Lee-Metford rifles, the CLLE's weren't even developed until the Boer War had ended.
Factual error: When they first meet, Rodrigues tells Blackthorne that aboard his ship there is plenty of food and grog. The problem is that grog was not "invented" until 1740, when it was introduced into the British Navy by Admiral Edward Vernon, who was nicknamed "Old Grog" because of his habit of wearing a grogram coat.