Pierette (Fanny Ardant) tells Augustine (Isabelle Huppert) that she looks like a woman from one of her romance novels, "La Dame Aux Camélias". Huppert actually played Alphonsine in Storia vera della signora dalle camelie, La (1980), an adaptation of that novel.
When Pierrette and Gaby roll on the floor and, after struggling violently, ended up starring a lesbian kiss, they who are kissing each other are actually Fanny Ardant and Catherine Deneuve, two fetish actresses for François Truffaut.
Of the eight musical numbers, it's only two that all eight women are present for: Pierrette's and Mamy's. In contrast, the musical number with the least amount of characters present is Chanel's, as she's completely alone for its entire duration.