In 1997, baseball commissioner Bud Selig universally retired Jackie Robinson's number, 42. The handful of players still wearing the number were allowed to keep it. As of the film's release, only Mariano Rivera of the New York Yankees continued to wear 42 on a daily basis. Rivera retired at the end of the 2013 season. As of 2014, barring special requests or approval, no major league player will wear #42 again.
Pee Wee Reese's line that someday all Dodger players might be wearing the number 42 was actually said by Dodgers outfielder Gene Hermanski in 1951. Brian Helgeland liked the quote so much, he had Reese say it because he is a central character. Since 2004, every April 15th has been "Jackie Robinson Day" in Major League baseball, and every player wears number 42. Robinson's first day in the Major Leagues was April 15, 1947.
The film does not explore Jackie Robinson's career with the Montreal Royals, but he was hugely popular. After leading the team to the league championship, it was noted: ..."probably the only day in history, that a black man ran from a white mob that had love, not lynching, on its mind."
The movie sanitizes Leo Durocher's speech to the Dodgers on the eve of their planned strike in protest of the signing of Jackie Robinson. His actual quote was "Don't care if the guy is yellow or black, or if he has stripes like a fucking zebra, I'm manager of this team, he plays!"
In the movie, the punishment for not agreeing to play on the same team with Jackie Robinson was being "traded to Pittsburgh". Branch Rickey left the Dodgers in 1950, and become general Manager of the Pittsburgh Pirates in 1953. Bobby Bragan, who said he wanted to be traded but then asked not to be, ended up managing the Pirates in 1956.
When calling the catch of a fly ball in the movie, broadcaster Red Barber says "Back, back, back..." In another play-by-play call, he exclaims "Oh, Doctor!" Contrary to popular belief, Barber didn't use either line regularly. Barber said the only time he used those lines in a broadcast was when he called Al Gionfriddo's dramatic, game-saving catch off of Joe DiMaggio in the 1947 World Series. Since recordings of that Barber call became so famous, many people assumed they were trademark calls.
The Birmingham (Alabama) News reported that Birmingham's Rickwood Field, the oldest surviving professional baseball field in the US, "played" three different roles in this movie. It doubled for Franklin D. Roosevelt Stadium in Jersey City, New Jersey, and Forbes Field in Pittsburgh, Pennsylvania, which no longer exist. It also appeared as "itself" in a scene recreating the 1945 season when Jackie Robinson was a member of the Kansas City Monarchs.
The last scene of the movie takes place at Forbes Field in Pittsburgh. As Jackie Robinson rounds the bases for his home run, one shot includes the Cathedral of Learning, a famous building at the University of Pittsburgh. In real life, Forbes Field was right next to the university. Forbes Field was torn down after the Pirates moved to Three Rivers Stadium in 1970, and the university kept home plate in its exact location. Forbes Field's home plate is encased in the ground at the same location as in the movie, in William Posvar Hall at the University of Pittsburgh.
While it is true that Jackie Robinson didn't get a hit in his first game, he did get on base via a throwing error by Bob Elliott, third baseman for Boston. He scored later, when Pete Resier hit a double.
In the movie, Branch Rickey punishes some of his rebelling players by trading them or threatening to trade them, to the Pittsburgh Pirates, in that they were one of the worst teams in the National League. Coincidently, in 2013, the same year the movie was released, the Pirates ended a streak of 20 straight losing seasons, going 94-68 and making the playoffs.
Robinson was not the first black major league baseball layer, but the first in the 20th century. The first black major league player was Moses Fleetwood Walker in 1884 on the Toledo Blue Stockings. He was followed by his brother Weldy. There is some good evidence the Walkers may have even been preceded by yet another player named William White.