When flying the plane, you can do stunts like siderolls and loopings!

Here's how:

When flying the plane (anytime and with any character) simply move the steering stick in one direction (up, down, left or right) and tap R twice quickly.

This will result in one of the following:

Upwards Loop (Up + Double R)
Downwards Loop (Down + Double R)
Sideroll Left (Left + Double R)
Sideroll Right (Right + Double R)

This is useful when you need to dodge some obstacle, or if you are really skillful, dodge a hazard like a rocket or a green gas cloud. Or you can simply show off!

Have Fun!