The Man in the Iron Mask evidently didn't aim at realistically depicting the reign and time of King Louis XIV.
- Louis XIV really had a brother named Philippe
, but that's where the similarity ends. Philippe wasn't Louis's twin brother and his life had never been a secret. - Louis XIV is depicted as unmarried, but in 1662 when the film is set, he'd already been married for two years.
- Contrary to the Hellhole Prison depicted here (and to be fair, in most every other depictions), the real Bastille prison was mostly used to house aristocrats and other upper-class prisoners, and most of them had a Luxury Prison Suite, not the dank filth encrusted cells like in the film.
- The real Man in the Iron Mask was arrested in 1669 or 1670. But to be fair, there is nary a similarity with the one in the film beyond being a mysterious masked prisoner in the Bastille.
- At no point is it made clear that the Jesuits are a religious order of priests and brothers, properly known as the Society of Jesus. Aramis, their head, identifies himself as the "General of the Order of Jesuits", while the correct term is "Superior General of the Society of Jesus". Besides Aramis, the other Jesuits in the film don't wear clerical clothing, so it makes them look like a cabal akin to the Assassins or Templars in Assassin's Creed - especially since a Jesuit (or suspected Jesuit) in disguise tries to kill Louis. Far from being an underground and persecuted sect (and neither evil), the Society of Jesus was one of the most influential Christian congregations in the Early Modern Period, running numerous schools and universities. While the Jesuits admittedly did face suppression in many parts of the world — particularly England in the 1500s-1600s, where the Jesuits were forced underground and heavily persecuted — for the rest of the world this didn't happen until the eighteenth century. Furthermore, in real life Louis never had any problems with the Jesuits; he was actually influenced by them in the latter half of his reign, and he had a Jesuit confessor. He did, however, order the persecution of the Huguenots and Jansenists, both of which were persecuted theological movements in France (the Jesuits were the latter's' rivals within Catholicism, in fact).
- The ending narration says that Louis XIV (Philippe, in the film's context) brought his country and his subjects "prosperity and peace". In Real Life, Louis spent most of his reign waging war, never changing his ways - as well as persecuting religious minorities such as the Huguenots and Jansenists - and the utter mess he left France in is often considered to be one of the causes of The French Revolution in the long run, along with the inability of his successors to structurally reform the Ancient Régime.
- It makes more sense that this should be understood as an Alternate History fairytale, not a mistake, per se; a sort of "if our dear heroes had been there, they could have saved the other prince and we would have known peace and prosperity!". Some serious Wild Mass Guessing fodder here.
