To get another view of the Crazy Taxi proceedings, begin a game. While the game is in progress press and hold L1 and R1, then press CIRCLE to enter first person driving mode. Press TRIANGLE (while holding L1 and R1) to show things from a wider angle. Press SQUARE (while holding L1 and R1) to see the speedometer.
At the character select screen hit L1+R1 three times quickly. You will now be able to drive a fast taxi bike. If you can't get this trick to work -- you can also gain access to the bike once you beat all Crazy Box challenges. Simply press D-Up at the select screen to get it.
To make the arrow that points you to your next destination disappear, hold R1 and press START before you see the character selection screen. "No Arrows" will appear on the screen if entered correctly.
To switch off the glowing square that indicates your destination, press and hold L1, then press Start before you see the character selection screen. "No Destination" will appear onscreen if done correctly.
To shake things up in the city and play "Another Day," press and hold R1. Keep holding it until you choose a taxi driver. Once you do, you'll see "Another Day" onscreen, indicating correct code entry.
To unlock the special Expert Mode, press and hold L1 and R1, then press START before you see the character selection screen. "Expert" will appear onscreen if done properly.