The Mushroom Planet has a muggy brown sky with a piercing sun. The planet has a breathable atmosphere, but is uninhabited. The surface of the planet cannot be seen, being covered entirely in mushrooms in all sizes that are so dominant that they grow on top of each other. According to Sonic, the mushrooms on the Mushroom Planet are "gross" and "smelly". There is also water on the planet, and it seems to possess at least two moons.
Sonic the Hedgehog
After spending three months of the planet, Robontik lost his grasp on his sanity. With some remains from his Eggpod and one of Sonic's energized quills, Robotnik would scour the Mushroom Planet with a stone he replaced Agent Stone with, confident that he would be able to return to Earth soon.
- The Mushroom Planet is most likely based on Mushroom Hill Zone from Sonic & Knuckles.
- The symbol on Sonic's map for the Mushroom Planet is of silhouettes of mushrooms from the Zone.
- In Sonic the Hedgehog: The Official Movie Novelization, it was stated that the Mushroom Planet consisted of a giant forest with mushrooms in every size, similar to Mushroom Hill Zone.
- In the first trailer of the Sonic the Hedgehog film, the sky of the Mushroom Planet was turquoise, resembling that from Earth. However, in the actual film, it is light brown-colored.