The plot of "Moliere" was actually loosely based on two of his plays, 'Le Bourgeois Gentilhomme' and 'Tartuffe'.
The opening scene of this gorgeous movie was filmed in Marie Antoinette's tiny private opera house, known as The Queen's Theatre, located at The Petite Trianon at Versailles. However, The Queen's Theatre was not constructed until 1780 - so approximately 122 years later than this film's opening scene time period of 1658. The Queen's Theatre can also be seen prominently in Marie Antoinette (2006).
The production hired a beautiful ancient harp from the Museo dell'Arpa Victor Salvi (Italy); the harp is dated 1760, so it is actually much later than Moliere's time.