Dermot Mulroney actually plays the cello in real life. He is a classically-trained cellist who began playing in Alexandria, Virginia's public school system when he was 7. He plays with the scoring orchestras on many films for Academy-Award-winning composers such as James Newton Howard and Michael Giacchino.
Rupert Vansittart appeared in both the 1994 film and the 2019 mini-series Four Weddings and a Funeral. He had the part of "George the Boor" in 1994, and portrayed Kash's boss at Goldman Sachs, also called "George". It's unclear whether it's the same character.
Several of the friends live in the London neighborhood of Notting Hill. Hugh Grant, who starred in the movie version of Four Weddings and a Funeral, also starred in the movie Notting Hill. An additional homage to Notting Hill is the "Ain't No Sunshine" montage, where Kash walks through the market over the course of a year, just like Hugh's character does.
As per Mindy Kaling's Instagram, principal shooting began in London in November 2018
Maya, Craig, Duffy, and Ainsley all share the same first line (the F word) in each of their introduction scenes.