Scott Patterson, who played Twins pitcher Mike McGrevey, had actually been a professional baseball player, pitching on the Minor League level in four Major League organizations during the 1980s prior to becoming an actor.
The one game playoff between the Twins and Mariners lasted twelve innings. In 2009, during their last season at the Metrodome, the Twins actually played a one game playoff which would last twelve innings. Interestingly that was also a season during which the Twins owner (Carl Pohlad) died and left the team to family members.
John Gordon, who played broadcaster Wally Holland, was the real-life voice of the Minnesota Twins until he announced his retirement after the 2011 season. While his use of silly statistics (e.g. batting average against left handed pitchers faced at home for the first time in the last month of the season) is a parody, he did use his trademark home run call when he said "Touch 'em all, Mickey Scales!"
In a film that contains many references to baseball history, the most subtle is that of the Twins pitcher named Mike McGrevey (Scott Patterson). In the early 1900's in Boston, there was a saloon keeper with that name who led a group of Boston Red Sox fans called the "Royal Rooters". (Today, they would considered a "fan club")They would enter in a large procession and sit in the lower left field stands of the old Huntington Ave Grounds (and later, Fenway Park). The Rooters, who were often drunk, were known for viciously taunting opposing players and playing music throughout a game with a marching band that accompanied the Rooters. Their biggest claim to fame in baseball history came in the 1912 World Series when they became so disruptive that they delayed game seven of the Series. The Red Sox eventually won that World Series in eight games (Game 2 ended in a tie and was called for darkness, forcing the Series to go beyond 7 games)
The baseball team in the original script were the Kansas City Royals before being rewritten and changed to the Minnesota Twins because it would be much easier to shoot in the Metrodome, an indoor stadium.