Elizabeth Gillies (Gigi), having a past in musical theatre, performs each of the show's original songs live on set.

Robert Kelly learned to play the drums for the role of Bam Bam.

The producers were looking for a girl who could sing live, do comedy, drama, and improv. Jim Serpico's teenage sons suggested Elizabeth Gillies as they were fans of the Nickelodeon musical series Victorious. Jim didn't think a Nickelodeon actress could fit into an FX series but Denis heard her sing immediately put the preconceived notions of Nickelodeon behind them.

Main characters are close friends in real life.

Gigi mentions Ariana Grande and her fame in several episodes. In real life, Elizabeth Gillies, who portrays Gigi, is good friends with Grande.

Callie Thorne also appeared in Rescue Me, which Denis Leary starred in.

John Ales had knowledge of guitar and bass guitar but was surprised he was chosen to be a bass player and had to learn for that part.