Po's kart is in the form of a fireworks wagon, a vehicle he used in the final battle of Kung Fu Panda (2008).
All the DreamWorks characters with ties to dragons have dragon-styled karts: Donkey with his love interest Dragon, Hiccup and Astrid who rode dragons, and Po the Dragon Warrior.
Every playable racer has access to a selection of custom parts designed to represent the famous DreamWorks logo (the blue clouds as the chassis and the Moon Child on the tires).
The Trolls were initially planned to appear as playable racers. However, due to their small stature disagreements occurred with the game developers over increasing their size to fit into the karts, so they were instead made power-ups.