When Billy Beane visits Fenway Park, the Red Sox championship banners from 2004 and 2007 are visible, though this takes place in 2002. Also, the seats above the "Green Monster" are visible, the seats were not completed until the beginning of the 2003 season.
In various scenes in Art Howe's office, there is a photo of 1971-3 A's manager Dick Williams with the Hall of Fame logo. Dick Williams was elected to the Baseball Hall of Fame by the Veterans Committee in December 2007.
In the montage where Billy is talking to his players about his new ideas, you can see a Mountain Dew can on the table with the new MTN DEW logo, this logo didn't come out until 2008 but the movie takes place in 2002
Peter Brand wears an all-green Oakland A's cap with yellow logo and a black-colored under-bill. However the black-colored under-bill was not a feature for New Era caps until 2007, when they debuted 100% performance polyester caps with the black-colored under-bill to reduce glare.
In a flashback where Billy Beane is playing for the Mets, he strikes out swinging and the umpire yells "strike three." It is universal professional umpire protocol to only vocalize called strikes. Swinging strikes are always indicated by hand signals only.
When Billy is talking to Mark Shapiro on the speakerphone, he realizes that the other buyer for Ricardo Rincon is San Francisco. Mark was never muted, but Billy then presses a button on the speakerphone and says "call you back", but doesn't press any buttons after that to hang up. This means Billy actually hung up on Mark and then said, "call you back".
When Billy Beane starts listening to game #20 of the streak in his truck there is a train crossing a bridge in the background. However, there is no bridge in the next shot of him veering toward an exit.
During the top of the fourth inning of game #20 of the streak, Raul Ibanez of Kansas City is at third base when the stadium announcer can clearly be heard saying, "Now batting . . . number 18 . . . left fielder . . . Raúl Ibañez."
As Billy is listening to game 20 of the streak on the radio, the announcer says Raul Ibanez is now batting. When Billy turns around and gets back to the stadium, it is the same inning, and the stadium PA announces Raul Ibanez is now batting.
In scene where Pitt and Hill's characters are trading players, Pitt has a coffee mug on his desk that usually is oriented to show the word "DAD". But in some cuts, the mug is oriented differently so the word is not visible to the camera.
Art Howe was not in the final year of his contract in 2002 with the Oakland A's as depicted in the movie. However he was gladly released from his contract at the end of the 2002 season by Billy Beane and hired by the New York Mets for the 2003 season.
Although the movie gets the trade of Jeremy Giambi correct (it happened early in the season and he was dealt for John Mabry), Carlos Peña was not traded until two months later, and not for a relief pitcher and cash. Pena was traded as part of a three-team deal with the Tigers and Yankees, which brought starting pitcher Ted Lilly to the A's.
In one of the film's flashbacks, Billy Beane is shown as a New York Met playing at Dodger Stadium against the Los Angeles Dodgers. As a player, Beane never played a game at Dodger Stadium, nor did he ever play a game against the Dodgers.
As the first example of his baseball know-how, Peter Brand shows Billy Beane a picture of Chad Bradford and tells the GM that the A's can get him cheap because every other team in baseball undervalues him. The problem is, this scene takes place following the 2001 season and Bradford had pitched for Oakland the entire 2001 season, after coming to the A's in a trade with the White Sox in December of 2000.
While it is true that David Justice played for the Yankees in 2001, Justice was acquired in a trade with the New York Mets on December 14, 2001 for LHP Mark Guthrie and RHP Tyler Yates. Justice was acquired only a week earlier by the Mets from the Yankees in exchange for Robin Ventura.
On the big board of free agents by team at the beginning of the movie, a player with the last name of Mathews is listed for St Louis as a right fielder (RF). The Mathews that was a free agent for the Saint Louis Cardinals at the end of the 2001 season was T.J. Mathews, a right handed pitcher (RHP).
In the 20th win game against KC, Mike Sweeney is shown hitting from the right side of the plate when he hit his home run. In the actual game, Sweeney was hitting from the left side of the plate when he hit the home run in left field.
The movie takes place right after the 9/11 attacks, when most non-passengers would not be allowed to say goodbye to passengers at the gate, inside airport security, as Billy Beane does. However, Beane is allowed to because his daughter is flying as an unaccompanied minor; as her guardian, he is allowed to escort her through security to the gate even though he is not flying.