• Jolie Hoang-Rappaport as Stevie Ting, a 12-year-old perfectionist. She also serves as the narrator of the film. • Hailey Magpali as a four-year-old Stevie Ting •
Kai Zen as an eight-year-old Stevie Ting • Elias Janssen as Elliot Ting, an aspiring magician who is the younger brother of Stevie • Francis Benson as a four-year-old Elliot Ting •
Craig Robinson as Baloney Tony, a plush giraffe •
Simu Liu as Michael Ting, the father of Stevie and Elliot who is an aspiring rock musician •
Cristin Milioti as Joanne Ting, the mother of Stevie and Elliot who works as a teacher and used to do music with Michael •
Omid Djalili as the
Sandman, the ruler of the dream world •
Gia Carides as Nightmara, the Queen of Nightmares • Erik Benson as Delilah, an expired muffin in Breakfast Town who keeps claiming that she is a "perfect princess" • Zachary Noah Piser as Joon Bae, a teenager who does odd jobs like a worker at the thrift store Shiver Me Thrifters and performing the Polly's Pizzeria mascot Polly •
Bob Bergen as a blue clown pacifier that appears in Stevie's nightmare • Maisie Benson as Cereal Girl, an inhabitant of Breakfast Town •
Jorge Diaz as Sausage Dog, an inhabitant of Breakfast Town • Quinn Minichino Eakens as the Bluberrries, the inhabitants of Breakfast Town •
Lizzie Freeman as Sandling #1, a minion of the Sandman •
Kellen Goff as Sandling #2, a minion of the Sandman •
Scott Menville as Sandling #3, a minion of the Sandman •
SungWon Cho as Chad, an uninterested Sandling that works for the Sandman • Alex Cazares as Scary Grandmother, the nightmare version of Joanne's mother and Stevie and Elliot's grandmother • Reece Warren as Stevie's friend with braces who appears in Stevie's test nightmare Additional voices by
Bob Bergen, Alex Cazares,
SungWon Cho, Hunter Clayton Dixon, David Errigo Jr., Kellen Goff,
Matthew Yang King,
Cristin Milioti,
Tara Strong, and Miriam Wallen. ==Production==