Factual error: In the opening game of the movie the announcers at the ball park are referring to the visiting team as the Peninsula White Sox. The team shown on the field is the Hagerstown Suns. (00:07:00)
Factual error: In a flashback to his youth, one of the bullies is wearing a Bartles and James T-shirt, which is a product that didn't exist in the early 70's.
Factual error: During Gavin Grey's first NFL game in 1957, the helmets depicted for both the Washington Redskins and Pittsburgh Steelers are historically inaccurate. The Redskins did not employ the burgundy helmets with the feather-stripe running along the center until 1958, and the Steelers didn't use black helmets with the Steelmark logo until 1963. In 1957, the Redskins used solid gold helmets while the Steelers used yellow helmets with a black stripe along the center and black numerals on either side.
Factual error: The movie takes place during the year 1919. Yet before one of the World Series games the stadium announcer requests that everyone stand up to sing "the national anthem". The US did not have a national anthem until the 1930's when Frankin D. Rosevelt signed into law the Star Spangled Banner as the nation anthem.
Suggested correction: According to Ken Burn's "Baseball", Burns and Ward verify that "The Star Spangled Banner" was sung at a baseball game in 1918 to support the efforts of American Troops in WWI- in which players like Ty Cobb, George Sistler, and Christy Mathewson all fought.
The mistake is saying the announcer called it the national anthem, not that they sung "The Star Spangled Banner."