Expert difficulty settings:
Press C-Up(4), C-Right(6), C-Down(2), C-Left(2) at the title screen. The sound of a scream will confirm correct code entry. Enter the options screen to access more difficulty settings.

Snow stadium:
Win J-League mode, then create an original team in edit mode. Enter the tournament mode and enter the first four letters of the tournament as "ha-do-so-n". The Snow stadium will be unlocked in tournament mode. Win the tournament to unlock it on all other modes.