The choir that sings "Face Your Fears" is The South Bay Children's Choir. Rachel Bloom was a member in her youth, and the same choir director was still at the helm.
For Paula Donna Lynne Champlin's big number, the writers developed a song called "You Gotta Get What You Can Get When You Can Get It," in which she reveals her philosophy on life and encourages Rebecca to be selfish. The song didn't properly fit the story's tone, so it was ultimately replaced with "Face Your Fears".
While brainstorming for the song "I Have Friends," Michael Hitchcock threw out the line "Grocery clerk with half an eyelid!" Everyone was so amused that they created the role of grocery clerk Brody (portrayed by Benjamin Siemon).
Tovah Feldshuh (Rebecca's mother) spent more than two hours in the chair as the makeup team took 20 years off of her appearance for the flashback sequence.
Rachel Bloom's demo of "I Have Friends" is included on the "Season 1 - Volume 1" soundtrack. There's no orchestration, she merely clapped her hands to establish a beat.