OK K.O.! Let's Take A Journey to the Center of the Earth

'OK K.O.! Let's Take A Journey to the Center of the Earth' is a direct-to-video film which is a crossover film between ''OK K.O.! Let's Be Heroes and Steven Universe'' for the third time.

Summary
After K.O. and Steven accidentally fall into the wishing well, they must find a way to get out of the wishing well. but soon discovered that something unexpected that they have never seen before in the whole life.

Cast

 * Courtenay Taylor as K.O.
 * Ashly Burch as Enid
 * Ian Jones-Quartey as Radicles and Crinkly Wrinkly
 * Kate Flannery as Carol
 * David Herman as Mr. Gar and Brandon
 * Melissa Fahn as Dendy
 * Kali Hawk as Red Action
 * Ben Jones as A Real Magic Skeleton
 * Zach Callison as Steven Universe
 * Estelle as Garnet
 * Michaela Dietz as Amethyst
 * Deedee Magno-Hall as Pearl
 * Shelby Rabara as Peridot
 * Jennifer Paz as Lapis Lazuli
 * Tom Scharpling as Greg Universe
 * Kimberly Brooks as Jasper
 * Tracy Morgan as Captain Caveman
 * Kiersey Clemons as Dee Dee Sykes

Featured species

 * Giganotosaurus
 * Edaphosaurus
 * Argentinosaurus
 * Pterosaurs
 * Deinonychus
 * Elasmosaurus
 * Tylosaurus
 * Archaeopteryx
 * Archelon
 * Giant Mastodon
 * Haast's Eagle
 * Megalania
 * Cave Lion
 * Cave Bear
 * Phorusrhacos
 * Arsinotherium
 * Troglodyte
 * Mole King
 * Giant Tortoise
 * Giant Green Iguana
 * Devonian Fish
 * Venomous Amphibian