Gate

Gates are commonly found obstacles that appear at the end of almost every Zone. They are silver doors that can only be opened by hitting the button or buttons that appear nearby.

1-Button Gates
1-Button Gates have a single button on the top. Garden 3 is the only exception -- because of the second half's spinning, and due to the fact it rotated for longer in the original cut due to the "Endless Mode" tunnel, its button now appears on the bottom. They appear after the following:
 * Forest
 * Forest 1
 * Forest 2
 * Forest 3
 * Mountains
 * Mountains 1
 * Mountains 2
 * Mountains 3
 * Mountains 4
 * Caves
 * Caves 1
 * Caves 3
 * Caves 4
 * Volcano
 * Volcano 2
 * Volcano 3
 * Ocean
 * Ocean 2
 * Ocean 3
 * Ocean 4
 * River
 * River 1
 * River 3
 * River 4
 * City
 * City 1
 * City 2
 * City 3
 * Garden
 * Garden 3 (Upside-down)
 * Castle
 * Castle 1
 * Castle 2
 * Castle 3

2-Button Gates
2-Button Gates have two buttons on either side of the door. They appear after the following:
 * Caves
 * Caves 2
 * Volcano
 * Volcano 1
 * Ocean
 * Ocean 1
 * Garden
 * Garden 1
 * Garden 2
 * Sky
 * Sky 1
 * Sky 4

Automatic Gates
Automatic Gates have no buttons nearby, and will open by themselves as the player passes through them. They'll always appear after a Zone at x4 Speed, and at the end of a Division before Endless Mode. They appear after the following:
 * Sky
 * Sky 2
 * Castle
 * Castle 4

No Gates
Rarely, a Zone will have no Gate after it and will simply proceed to the next zone without having to open anything. They appear in the following:
 * River
 * River 2
 * Garden
 * Garden 2
 * Sky
 * Sky 3