Crazy Taxi

No arrow indicator
Just before the driver selection screen appears, hold R + Start.
If the code is accepted, you should see the message "No Arrows"
in the left corner of the screen.

No destination indicator
Just before the driver selection screen appears, hold L + Start.
If the code is accepted, you should see the message "No Destination Mark"
in the left corner of the screen.

Enable Expert mode
Just before the driver selection screen appears, hold L + R + Start.
If the code is accepted, you should see the message "Expert"
in the left corner of the screen. There is no any kind of indicator
in this mode.

Another Day mode
Go to the driver selection screen, Press and hold R while selecting a
driver. If the code is accepted, you should see the message "Another Day"
in the left corner of the screen.

Secret Push Bike:
Go to the driver selection screen, press L + R , L + R, L + R then
hold L + R and press Up or Down while selecting your character.

Special Taxi
Go to the driver selection screen, then press L, R, L, R, L, R or
L + R, L + R, L + R. After, choose any of the characters to
drive a bike.

Bonus levels in Crazy Box mode (Japanese version)
Reach an S license with all 4 characters in arcade mode

Crazy Dash: Press Accelerate + Drive.
Crazy Stop: Press Brake + Reverse.