Once Upon a Time Machine is the second Easter episode of the 1987–1996 animated Teenage Mutant Ninja Turtles series. It originally aired over CBS aired on 29 March 1991, during the series fourth season. While not so Easter-themed as The Turtles and the Hare, it features the Easter Bunny Hokum Hare from "The Turtles and the Hare" assisting the turtles in preventing Shredder to time travel into the future and rule it.
Family Home Entertainment released the episode on a VHS tape titled The Turtles' Awesome Easter in 1993, together with The Turtles and the Hare. The episode was later released to DVD on the Teenage Mutant Ninja Turtles: Season 4 DVD set, released by Lionsgate Entertainment in Region 1 on 13 March 2007.