D'Artagnan did really exist. His name was Charles de Batz and was called D'Artagnan after he arrived in Paris, probably because he came from the commune of Artagnan in the south-west of France (where the movie was partly shot).
The first film that director Peter Hyams had directed without his long time editor Steven Kemper, who vowed not to work with the director after the last few films he had directed which included La Fin des temps (1999) and Relic (1997) were too darkly lit and shot causing editorial problems.
One of a few Peter Hyams movies that do not contain a character (or place) called Spota, which is his wife's maiden name.
The first film the director Peter Hyams did not work with his usual composer John Debney, who had composed the music for Mort subite (1995), Relic (1997), and La Fin des temps (1999) for Hyams.
The first collaboration between director Peter Hyams and editor Terry Rawlings. Hyams' usual film editor was Steven Kemper, but after the last few films that Hyams had directed caused editorial problems lighting wise, Kemper decided not to work with him again.