When the novel "Les Liaisons Dangereuses" by Choderlos de Laclos was first published in 1782, it was considered so scandalous that when Queen Marie Antoinette commissioned a copy for her personal library, she had to have it bound in a blank cover so that no one would recognize the author's name or title.
Michelle Pfeiffer was offered the role of the Marquise de Merteuil in Valmont (1989), but she chose to play Mme. de Tourvel in this film instead.
Alan Rickman made the role of Valmont famous in London and on Broadway. However, filmmakers wanted to cast an established actor in the role, so Rickman wasn't even considered. Rickman ended up making his Hollywood debut as Hans Gruber in Die Hard (1988) instead.
Director Stephen Frears and screenwriter Christopher Hampton were so taken upon meeting Mildred Natwick, they hadn't realized that they'd forgotten to offer her the part of Valmont's aunt until after they'd parted company.
Glenn Close was unavailable until midway through filming due to having just given birth to her daughter.