Following the trend set by Green Hill and Casino Night, Mushroom Hill Act 1's level layout is a complete recreation of the original Mushroom Hill Zone Act 1 in Sonic & Knuckles. Like in the original Zone, there is even a Star Post that has been placed just before the Goal Plate, although it no longer plays a large role, as Hei Hou does not appear in this Act. In addition, any secret rooms in this Act that would have contained a Giant Ring in Sonic & Knuckles now hold a cluster of Rings instead.
Unlike the more lush first Act, Mushroom Hill Act 2 takes place during the fall, like the original Zone in Sonic & Knuckles. Also, a particular gimmick found in this Act is the Seed Propeller, a contraption that can carry Modern Sonic large distances through midair if he boosts into it at sufficient speeds.
Towards the end of the Act, the player enters a Grind Rail section that leads through a mushroom-filled cavern. It is worth noting that along this Grind Rail there will be hedgehog-eating plants that will cause an instant death if Modern Sonic collides with them without boosting. At the end of the Grind Rail section, the player must then break through a rock wall with a well-timed Homing Attack in order to reach the Goal Ring.
|026||Die-Hard||Clear Mushroom Hill Act 1 in 2:00.00 without losing a life!||Sound||Mushroom Hill|
|027||Ring Collector||Collect 60 Rings in Mushroom Hill Act 1 in 1:00.00!||Sound||Flying Battery|
|028||Keep the Pace||Grab Time Items and clear Mushroom Hill Act 1 in time!||Art||1994 Illustration|
|029||Rampage!||Defeat 10 enemies in Mushroom Hill Act 1 in 1:00.00!||Sound||Death Egg|
|030||Stealth Attack||Clear Mushroom Hill Act 1 in 2:00.00 without defeating enemies!||Art||Illustration 2|
|031||Item Collector||Get all Item Boxes in Mushroom Hill Act 1 in 2:00.00!||Sound||Angel Island|
|032||Special Trial||Defeat 5 Madmoles in Mushroom Hill Act 1 in 1:00.00!||Model||Knuckles|
|033||Perfection||Clear Mushroom Hill Act 2 in 2:20.00 without taking damage!||Sound||Hydro City|
|034||Ring Collector||Collect 45 Rings in Mushroom Hill Act 2 in 1:00.00!||Art||1995 Illustration|
|035||Keep the Pace||Grab Time Items and clear Mushroom Hill Act 2 in time!||Sound||Marble Garden|
|036||Rampage!||Defeat 10 enemies in Mushroom Hill Act 2 in 2:00.00!||Sound||Door into Summer|
|037||Stealth Attack||Clear Mushroom Hill Act 2 in 3:00.00 without defeating enemies!||Art||1996 Illustration|
|038||Special Trial||Use Seed Propeller to get 70 Rings in Mushroom Hill Act 2 in 1:00.00!||Model||Amy|
The following are the suggested clear times for achieving a high enough score to achieve each Rank:
|Act 1||0:00.00 - 1:35.00||1:35.01 - 1:45.00||1:45.01 - 2:00.00||2:00.01 - 2:15.00||2:15.01 - 9:59.99|
|Act 2||0:00.00 - 1:45.00||1:45.01 - 2:00.00||2:00.01 - 2:50.00||2:50.01 - 3:25.00||3:25.01 - 9:59.99|
- The giant flower propellers from Modern Sonic's stage look similar to the ones from Frog Forest and Egg Fleet in Sonic Heroes.
- This is the only stage from Sonic Generations where the levels are based off of two different Acts of the same level, which is why they have different seasons/themes.
- Seaside Hill and Water Palace are similar, except that both Acts they were originally based on were merged into one for each Sonic (Water Palace did this for Modern Sonic only).
- Tropical Resort also did something similar, however it is based off the first Act of 2 different versions of the level instead of both acts of the same version
- Act 1 has the same layout as Mushroom Hill Act 1 in Sonic & Knuckles.
- Because of this, there is a checkpoint that is right next to the goal post, as the player would face Hei Hou after passing that check point in Sonic & Knuckles.