Sonic the Hedgehog and the Freedom Fighters visited this Zone to talk to Knuckles the Echidna about joining forces against Doctor Robotnik. They were intercepted by Predicto, who used the Zone's mushrooms to attack Tails, Johnny Lightfoot and Porker Lewis. Knuckles attemped to help by sneaking underground, but Predicto had already anticipated this and captured him. Sonic eventually defeated Predicto by surrendering, confusing it into self-destructing. Knuckles quickly threw the heroes out of the Zone and off his island.
- The name comes from the Mushroom Hill Zone's label in the Sonic the Hedgehog 3 level select.