

Uniqua and Pablo are a cowgirl and a jockey. When they argue about who is a faster rider, they decide to settle the matter with a race to the end of the Mississippi River, with Austin serving as the announcer. To their surprise, Tyrone enters the race on a tired, old-looking donkey named Burro. As the race progresses, the two make a quick dash for the finish, but Tyrone and his donkey gain ground as the two continuously stop to argue who is better.
When the Backyardigans receive a strange signal originating from Mars, Uniqua, Pablo and Austin blast off to investigate. They're backed up by Tyrone and Tasha, who remain on Earth to assist at Mission Control. The Backyardigans leave prepared for anything, but encounter some surprises along the way. They don't give up, however, and eventually make a surprising discovery regarding the source of the signal.
Pie makers Tyrone and Austin must make a pie for Empress Tasha, while protecting it from Ninjas Uniqua and Pablo.