The stadium that the South Park Little League Baseball Team played in for the State Championship Game is Coors Field (http://colorado.rockies.mlb.com/col/ballpark/index.jsp) located at 2001 Blake Street, Denver, Colorado, United States 80204.
"Whistlin' Willy's Pizza Gultch" is not a real restaurant but is believed to be a parody of the restaurant "Chuck E. Cheese's," http://www.chuckecheese.com. which are located all throughout the United States.