The scene in Adam's movie that shows how Hannah and Adam met was proposed as a flashback scene in season 2 by Lena Dunham, and rejected by the writers' room.
Elijah says "If I'm saying that I'm a Broadway-caliber actor, shouldn't I only be auditioning for things that would take place on Broadway?", Andrew Rannells (who plays Elijah) is a Broadway actor, and he appeared in musicals such as "Hairspray", "Jersey Boys" and "The Book of Mormon".
This episode features the premiere of Robyn Carlsson's song "Honey". The song was not ready to be released, but Carlsson finished it especially for Lena Dunham in order that it could be featured over the end credits. Dunham's character, Hannah, memorably dances to Carlsson's "Dancing on My Own" in the third episode of the first season.
The coworker Elijah practices lines with is Jasmine Cephas Jones, who played Peggy/Maria Reynolds in the original production of Hamilton. She is the second Hamilton actor to appear in this season of Girls (Desi's rehab therapist also starred in Hamilton).