Hidden Characters
Backyard Baseball 2003 features several of the most legendary players to hit the field. Babe Ruth, Mickey Mantle, Roberto Clemente and Mark McGwire can all be unlocked by entering "LEGENDS" as a coach's name.
Mr. Clanky can be unlocked for use in exhibition games simply by entering the clubhouse trophy room and clicking on his avatar.
Hidden Stadiums
Although the game includes several stadiums from the beginning, there are two hidden stadiums in Backyard Baseball 2003 that need to be unlocked before you can play there regularly. The Big City Superdome and the Super Colossal Dome can be unlocked by winning the Backyard World Series.
Never Lose a Game
Going a whole season as an undefeated team in baseball is practically unheard of, except in Backyard Baseball 2003. Make sure your team goes undefeated by restarting your computer or signing out of your Windows XP user name when you're facing a loss. As long as your progress has not been saved by entering batting practice, you can then restart the game to try it over.
Enhanced Performance Cheats
Some players in Backyard Baseball 2003 can take advantage of enhanced performance, depending on who they're playing with or on what team they're playing. Put Sidney and Ashley Webber on the same team to see an enhancement in both players. Put Ronny and Sally Dobbs on the same team to increase Sally's stats, and put Sammy Sosa on the Chicago Cubs as a right fielder to see an increase in his performance. If you place Marky Dubois on the same team with Billy Jean Blackwood, you'll notice an increase in Marky's stats. Billy Jean Blackwood's stats, though, will decrease as a result.
Easier Hits
To make sure your batters hit the ball every time, pause the game right after the ball has been pitched. Move your mouse pointer to where the ball is located, and unpause your game. You can hit the ball easier than ever before.