Sonic Colours/Bugs
From Sonic Retro
This is the bug list for Sonic Colours (Wii)
Behind the start in Asteroid Coaster
Its possible to get behind the start in Asteroid Coaster Act 5. Here is the glitch. Its possible that the player was meant to start further back.
3D in 2D and vice versa
Just like in Sonic: Unleashed, its possible to have 3D in 2D levels and vice versa. Here is an example.
Normal physics underwater
Apparently by pausing the game, the underwater physics can be broken. It even kills the drowning countdown. Here is an example.