The bat that bat boy Bobby Savoy gives Roy is called the "Savoy Special". The Savoy Special was a brand of beer in the 1930s, and was made by the United States Brewing Company. This bat is now in the collection at the National Baseball Hall of Fame and Museum in Cooperstown, New York, displayed along with Roy Hobb's jacket in an exhibit titled "Baseball and the Movies".
The two eras of the film show Roy Hobbs at age 19 and age 35. Robert Redford was 47 at the time of filming.
The filmmakers scouted the country for a stadium to use in game scenes. They needed something nondescript with a pre-World War II feel, and found it in Buffalo's War Memorial Stadium. The stadium, built in 1937 and demolished in 1988, had a shorter distance down the right field line than is shown in the movie. The stadium had been renovated prior to filming, which could explain the extra hundred feet displayed on the right field wall.
While Darren McGavin had a major supporting role as the bookmaker Gus Sands, he received no credit. In the recent retrospective documentary on the Special Edition DVD of this movie, Robert Prosky (the Judge) claimed McGavin was cast late in the picture, and would have received a lesser billing than the other stars. Thus McGavin chose to go uncredited. Prosky noted where McGavin wound up "drawing more attention to himself" as a result.
Hobbs breaking the scoreboard clock with a home run was inspired by Bama Rowell of the Boston Braves doubling off the Ebbets Field scoreboard clock on May 30, 1946, showering Dixie Walker with glass. Though he'd been promised a free watch by Bulova for hitting the company's scoreboard sign, Rowell had to wait until 1987 to receive it.
Barry Levinson: [Ralph Tabakin] (Al's customer) has appeared in every Levinson picture from Diner (1982) to Liberty Heights (1999). Levinson, a Baltimore native, is also an Executive Producer, and sometimes director, of Homicide: Life on the Street (1993), where Tabakin had a recurring role.