As said in the main page, despite being promoted as going into the history behind the legend, the film contains rather large deviations and inventions.
- According to the film, Robin Hood's father is responsible for a precursor of Magna Carta. Despite promising to give it his seal of approval, John doesn't and has Robin outlawed for his trouble. This does not contradict the fact of the real Magna Carta being signed several years into John's reign, which Scott plans to cover for real in a sequel, should it be greenlit. The production notes explain the charter is intended to represent the Carta de Foresta (Charter of the Forest), which awarded rights, privileges and protection to the common man (whereas Magna Carta was primarily concerned with the rights of noblemen). In the film, Robin's father drafts it years earlier. Yet John's refusal to approve it still does not contradict history, because the real Carta de Foresta came after Magna Carta, sealed by John's son Henry III.
- The main plot conflict is dodgy because King Philip never invaded England. At the time, he was much more interested in recovering Angevin territories in France than he was in invading the English mainland. Years later, when John broke the terms of the Magna Carta and many barons rebelled for real (unlike the film), Philip's son Louis led an invasion with their support.
- The film shows Richard dying from a crossbow bolt almost immediately. In truth, he lived for more than a week, succumbing to gangrene after a botched operation. He lived long enough to see the crossbowman (a boy who defended the walls with a crossbow and a frying pan — not a cook) brought before him. He forgave him (even after the boy confessed that he had shot Richard to avenge his father and brother) and ordered that he be set free and rewarded with 100 shillings for such a lucky shot. Shortly after Richard's death, the pardon was retracted by a mercenary captain, and the boy was flayed alive.
- Richard's death: the film explicitly mentions the year 1199. This is true. However, the circumstances of Richard's death are badly muddled. In the film it's stated that his death occurs as he's returning to England from the Crusades. In actual fact, the Third Crusade effectively ended in 1193 as Richard had to rush back to England after the political crisis fomented by John reached a boiling point. On the way home, Richard was shipwrecked in modern-day Croatia and taken prisoner just outside Vienna by an enemy of his from the Crusade, Duke Leopold of Austria. Richard would spend the next two years a captive of both Leopold and later Emperor Henry IV of the Holy Roman Empire, finally being released after much wrangling and a near-ruinous ransom was paid. Richard was finally released to friendly territory in the Angevin Empire, from which he made his way to England. There, John's forces almost uniformly surrendered without a fight to Richard (the one prominent holdout being, fittingly enough, Nottingham Castle, which did offer resistance), and Richard was free to rule again after a second coronation. It was a piddling rebellion on his marchlands that caused his death in April, 1199, not a skirmish during his return from the Crusades. The film also shows him as fighting Philip of France there, instead of a baron in his own land.
- Richard speaking English, bragging about his English heritage and directing slurs to the French during the first siege for that matter. In reality, all "English" monarchs and nobles between 1066 and 1453 were of Norman extraction and spoke the Anglo-Norman language, more like French than anything English. While they would have looked down on the rest of the French, they also would have considered English to be the language of peasants, and it is unclear if Richard spoke it at all. Richard himself was far more interested in controlling Normandy than England. England was most important to him as a source of wealth, and was more a somewhat important frontier land in the Angevin Empire than his cherished homeland. To Richard, "home" wouldn't even have been Normandy, the heartland of the Empire — it was his mother Eleanor's domain of Aquitane. England's main value is it allowed him the title of King. Otherwise, he was technically a vassal of the French king, although the English holdings in France were as or more valuable than what the French king held.
- The film also, and quite understandably, chooses to ignore the fact that Isabella was twelve when she married John.
- The film states that Richard had no children. The correct statement would be no legitimate children. He had one illegitimate child: Philip of Cognac.