Cristin Milioti — Grace
Delaney Quinn — Freddy
Topher Grace — Ben
Keegan-Michael Key — Buddy the Unicorn (voice)
Michael Shannon — Willie (voice)
Patton Oswalt — Strappy (voice)
Clint Howard — George
Eric Bauza — Mr. Mailbox / Worry Well / Couchy / Trashy / Pee Flower (voice)
Sergey Zhuravsky — Buddy the Unicorn (suit)
Jonathan Yurco — Dark Buddy (suit)