Factual error: The film is set in the year 1662. Louis is supposed to be in the middle of a war against the Dutch. This is actually not correct. The war against the Dutch didn't begin until 8 years later in 1672.
Factual error: Six years in a mask and Philippe's teeth are in perfect condition. All that time without brushing or flossing, you'd think he'd have lost some teeth or been in wracking pain from toothaches.