FIFA 2003 Codes -

Seoul stadium:
Win the International Cup to unlock the Seoul stadium.

Stade de France stadium:
Win the Club Championship to unlock the Stade de France stadium.

Hint: Easy goals from halfway:
When you start a match, change controls to the other team and hold Keeper Rush for the goalkeeper to rush out and get the ball. Pause game play while still holding Keeper Rush and change back to your side. The other goal keeper should keep rushing out and slide tacking you. Shoot from halfway and you should get a goal. Also for laughs, sometimes the goalkeeper grabs the ball meters from the box and nothing happens.