Factual error: When Dodge and Lexie are in the building running from the police, you see an exit sign. This movie is set in the 1920's, before exit signs were invented.
Factual error: The movie takes place in 1926 but when the announcer mentions a "Hail Mary" play near the end of the movie the term hadn't been coined yet. Dallas Cowboys quarterback and devout Catholic Roger Staubach was believed to have first used it after executing that play in a 1975 NFL NFC semifinal playoff game. (01:40:00)
Factual error: In the shot of the Chicago Skyline in the final game, you are able to see the Wrigley Building, Tribune Tower, Carbon and Carbide Building, and the Board of Trade Building. All Chicago landmarks of the era, but the field is north, say where Wrigley Field currently is, makes the angle at which you see the other buildings impossible. Also, there are two rather modern (1970s) box-like skyscrapers in the skyline that certainly did not exist in 1925.