It was long believed that since star Gary Cooper was right-handed and Lou Gehrig was left-handed, the close-up baseball scenes were shot with his uniform in reverse type. Cooper would hit the ball and run to third, and the prints would be reversed. But in an extensive bit of research, National Baseball Hall of Fame curator, Tom Shieber has shown that Cooper did indeed learn to bat left-handed and that in only one short sequence of the film was image reversal used in order to show Cooper throwing left-handed. Other scenes requiring Cooper to throw a ball were filmed using his stand-in, Babe Herman.
While filming the movie, Teresa Wright - who played Gehrig's wife Eleanor Gehrig - wore the actual bracelet that Lou gave to Eleanor on their fourth anniversary. Eleanor brought the bracelet to the set to be used in the movie. The bracelet is made up of 17 metal medallions that celebrate the seven World Championships and six All-Star game appearances that Gehrig made. The bracelet is now displayed in the Baseball Hall of Fame.
Lou Gehrig's famous retirement quote, "Today, I consider myself the luckiest man on the face of the earth.", was originally spoken on Tuesday, July 4th, 1939. And it was voted as the #38 movie quote by the American Film Institute (out of 100).
In reality, Gary Cooper was decidedly not a fan of baseball and required extensive coaching in order to look even passable on a baseball diamond. In fact, he had never played the game before, even as a youth, and had never even seen a baseball game in person until he was hired for this film.
When Samuel Goldwyn began looking for someone to play Lou Gehrig in "Pride of the Yankees," he quizzed baseball writers. The Sporting News polled the fans, and their pick was Cleavland Indians pitcher Johnny Humphries because of the strong facial resemblance. Goodwyn considered the candidates and chose actor Gary Cooper for the role.
Sportswriter Hank Hanneman (Dan Duryea) is loosely based on Hearst newspapers writer Ford Frick, who was the ghost writer of Babe Ruth's autobiography. Later as Commissioner of Baseball he attempted to list Ruth's and Roger Maris' season home run records separately to preserve Ruth's record.
Multiple published sources have asserted that Cooper, who was right-handed, could not master a convincing left-handed throw or swing. To remedy the problem, the story went, he was filmed throwing right-handed while wearing a mirror-image uniform, and for batting sequences he would swing from the right side of the plate, then run to third instead of first base; technicians then reversed the print of the film. However, Tom Shieber, a curator at the National Baseball Hall of Fame, has shown that Cooper did indeed learn to bat left-handed, and never wore a backwards Yankees uniform nor ran to third base after swinging. Film footage was "flipped" only once, during a brief sequence portraying Gehrig's minor-league days at Hartford, in order to make Cooper appear to be throwing left-handed. Scenes requiring Cooper to throw a ball as a Yankee were filmed using his stand-in, Babe Herman.