Marshawn Lynch was initially unsure about accepting the role. He ended up taking it as a way to rewrite his regret of mishandling his younger sister coming out to him in high school.
Ayo Edebiri and Rachel Sennott were roommates when they attended New York University. Emma Seligman also attended NYU at the same time, and the three were good friends.
When Josie is telling PJ about what her life's going to end up being (marry Matthieu, getting pregnant, he'll become a pastor, they'll have a son), it was all improvised by Ayo Edebiri.
Ayo Edebiri's character Josie and Havana Rose Liu's character first study at the diner named "But I'm a Diner," which references the lesbian-themed comedy film But I'm a Cheerleader (1999). The waitress who serves Josie and Isabel their food is named Natasha, presumably after Natasha Lyonne, the star of the aforementioned movie.