Other mistake: When the airship crash lands in the garden at the end of the film, D'Artagnan, Athos, Porthos, Aramis and Constance are all still aboard, along with the Queen's diamonds. However, only a minute or two later, the Queen emerges wearing the perfectly polished diamonds, and Constance is behind her, her hair, dress and makeup impeccable. This could not have been achieved in the time between the ship crashing and then.virtual-toast
Factual error: When D'artagnan and the musketeers are infiltrating the Tower of London, the king's guards are seen with the Tudor Rose crest on their tunics. By the time stated at the beginning of the movie, the last Tudor monarch (Elizabeth I) had been dead for 80+ years.