The outfit that Claire wears with the white jacket and black skirt is inspired by the famous Dior New Look (1947) outfit, one of the most famous single outfits in fashion history.
The title is a spin on the famous sentence uttered in The Wizard of Oz by Dorothy "(we're) not in Kansas anymore". Last season there were also references to The Wizard of Oz.
Collette is a squirrel monkey, which comes from South America. The bored French aristocracy, like most of the pampered, beautiful people of the time, would have paid a small fortune for a pet that exotic. Anything for a brief diversion.
Te Deum, the melody played at the French court, is know as the chosen theme of the European Broadcasting Union. All programming produced by them, like the Eurovision Song Contest, is introduced with this piece.
When Claire enters the apothecary, she asks for Mister Raymond. The assistant she is speaking to corrects her saying Master. France abolished slavery in 1794, some 50 years after this episode.