F-Zero X

All Cars, Tracks and Difficulties:
At the Mode Select screen, press L, Z, R,C-UP, C-DOWN, C-LEFT, C-RIGHT, START.
You should hear a chime if you did it correcly.

Change Car Colors:
To change your car's colors, simply press the R-Button during the car customization screen.
Note that there are only a few select colors for each vehicle.

Joker Cup:
To get the Joker Cup and six additional tracks beat the Jack, Queen, and King Cup on Standard difficulty.

Mute City II Shortcut:
Right after you make the third hard turn, you will see a ramp to the left that looks like it will lead you off track.
If you hit it with a booster, you will fly over the gap and onto the next strip of tracks.

Rotate Cars on Customization Screen:
Want to see your car from different angles?
At the customization screen press the C-Buttons to rotate the car in all directions.

Smaller Cars:
At the car select screen press and hold the (L) and (R) buttons.
While holding those buttons press C-LEFT and C-DOWN to shrink the cars.

Title Screen Changes:
To have the title screen change to a comic book motif, beat F-Zero X on Expert.
For a second change, beat the game on Master difficulty.

X-Cup (Track Generator):
Beat all four cups on Expert difficulty to open F-Zero's hidden X-Cup.
This cup will randomly generate six courses, ranging from utterly boring to plain cool.
Beating the four cups will also open a Master Difficulty level.