After the final game of the championship series, Jimmy Dugan tells Dottie Hinson he has an offer to manage the next season in Wichita, to which she replies, "Triple A." The AAA designation did not exist until 1946; before then, the top minor leagues had a AA designation.
In the Suds Bucket road house, on more than one occasion, you see a neon sign in the background for Augsburger Beer. Augsburger Beer was not produced until 1959. (Augsburger was originally produced by the Monarch Brewing Co. from 1959 to 1967, and then was brewed by the Potosi Brewing Co. Huber, located in Monroe, bought the brand in 1971 and made the beer until Stroh bought the label in the late 1980s.) The sign appears to be that of 1980's vintage.
During the tryout montage scene, we see a group of elderly women complaining on a broadcast on radio station WMGM. However, that station didn't go on the air for the first time until 1948, five years after the movie was set. Furthermore, WMGM was in New York City.
When Jimmy Dugan walks in to the locker room and urinates, he urinates into a trough which would not have standing water in it, but we hear the sound of someone urinating into a toilet with water in it.
In the scene where Marla is trying out in the gym and she hits the ball though the window you can tell that the ball is going though two different windows. The first shot is from inside the gym and the ball breaks through the window at the corner of the building in a direction towards the corner of the building. The next shot is from outside the building and the ball is not coming out of the corner window, but the window next to it, and not in the same direction as the ball was hit from inside the building. The angle at which the ball came out of the building would never be possible from where Marla was hitting the ball.
During the scene where Dottie's parents are listening to Maida Gillespie's radio broadcast, you can see in their magazine collection the Life magazine on which Dottie is on the cover doing the splits while catching the pop fly. That doesn't happen until later in the movie.
When all the girls must find their names on the list, we see Doris and Mae hugging each other because they both made the team. In the next shot, while Kit is pushing through the crowd to tell Dottie she had made it, she pushes by Doris who is still waiting to see the list.
There is an approximate 4.3 second gap where the camera cuts away from Jimmy holding an unfolded towel to Alice, before returning to Jimmy where the towel in his hand is now folded. It's not completely implausible that he could have folded the towel in those 4.3 seconds.
While Dottie is waiting for Kit to sign a girl's ball after the World Series game, we see a stadium vendor walk into the restroom behind Dottie. In the very next shot, he walks into the restroom again.
When the girls are at the Suds Bucket roadhouse we can see Ellen Sue on the floor dancing. When they cut away to show a boy kissing Kit on the cheek you can see Ellen Sue sitting down behind her, but when they cut back to the dance floor Ellen Sue can still be seen dancing.
When Kit and Dottie are talking in the locker room after the World Series' final game, Kit's hair is pulled back by bobby pins and her bangs are messy. However, a few moments later when Kit is getting into the Racine bus, as she's waving goodbye to Dottie, her hair has fancy barrettes and her bangs are neatly cut.
When Kit becomes unduly upset after the last game of the World Series, she is shown hunched over, weeping, and holding her mitt over her head, wearing her jacket over half her upper body; the camera cuts to Dottie watching her, Kit is shown again in a long shot, same posture, but the jacket is gone.
When the initial team tryouts are being held in an ivy-walled stadium (obviously Chicago's Wrigley Field) there is a shot of Betty Spaghetti running back to make a catch in the outfield in front of a plywood wall that is clearly from another field.
The Oregon Zephyr train is pulled by a model E-5A diesel-electric, distinctive by its rippled stainless steel side panels. These locomotives were used exclusively by the Chicago, Burlington and Quincy Railroad and its subsidiaries, the Colorado and Southern and the Fort Worth and Denver. None of these railroads ran through Oregon.
The pitchers are clearly seen using an overhand delivery. But the movie takes place during the AAGPBL's first year, 1943, when the game more resembled fast-pitch softball than baseball and an underhand delivery was used. Overhand pitching wasn't accepted as standard in the league until the late-1940s.
The end of the film notes that the players of the AAGPBL were "the first women ever to be inducted into the Baseball Hall of Fame." Actually, they are not inductees. Rather, they were recognized with a permanent exhibit in the National Baseball Hall of Fame and Museum, entitled "Women in Baseball," in 1988. The first woman to actually be inducted into the Baseball Hall of Fame was Effa Manley, the co-owner (with her husband, Abe) of the Newark Eagles. She was inducted in 2006.
When Dottie and Kit first meet Mae and Dorris at try outs, Kit looks around and comments, "Are all these girls going to be in the league?" It is then revealed that out of the 100 girls that were at try outs, only 64 girls would be select to make up four teams of 16 girls. 32 girls received train tickets home. During the actual 1944 AAGBL tryouts in Chicago, scouts sent 280 girls to the try outs, but only 60 girls were selected to form four team of 15. 220 girls were given train tickets home.
In the final game, a crowd shot shows a solider in his Class "A's" with service cap stand and cheer. The soldier wears the stripes of a corporal on his sleeve, but on his service cap he wears the eagle cap device of a commissioned Army officer, not the round cap piece of an enlisted soldier.
In the opening baseball scene, Dottie goes up to Kit and states there is a whole in right field so if an inside pitch she will have to pull it. A right handed batter pushes to right and pulls to left (especially if an inside pitch).
When Mae (Madonna) catches the ball in her cap, it's not an out. A player can not use any part of the uniform to trap or catch the ball. But that's a Major League rule; it's reasonable that they would allow this as an out in the AAGPBBL, especially since the league was looking for gimmicks to draw in customers.
In the beginning of the film Dottie's daughter says that she will miss her flight. However, Dottie took a bus to Cooperstown and no plane is ever shown. However, Dottie is coming from cross-country, and there isn't a major airport at Cooperstown. It is entirely feasible that Dottie flew to a nearby airport (Buffalo, Albany, or even NYC) and then bussed from there. Dottie can also be clearly heard saying "a plane, train, and then bus? I'm tired already".
The child actor playing Stillwell looks off camera (presumably towards the director) before falling, after he is hit with the baseball glove thrown at him. But he's stunned so he doesn't necessarily know where he is looking.
During Marla's tryout in Colorado, Marla's father says "now left handed" and Marla begins to hit left handed. The problem is that the pitchers change and proceeds to pitch left handed. In baseball a switch hitter hits from the opposite side of where the pitcher pitches. However, this isn't practice, it's a demonstration of Marla's abilities, so Marla can hit whichever side is necessary to show her off. The pitcher was just tired, and gave way to someone else.
The car in which Dottie and her husband drive off (presumably to Oregon) has an "A card" sticker for gas rationing. Would they be able to buy sufficient gas to drive to Yellowstone National Park and back to the Midwest during the course of a 7-game World Series, much less have the time to make the drive?
Lowenstein tells Dottie/Kit about Dottie helping get her kid sister in the league. Later in the film when Dottie is yelling, she says she got her into the league. The other players, who already know this fact, act surprised.
The goof items below may give away important plot points.
When the older Dottie is looking at Jimmy Dugan's photo and bio poster at the museum, the line "Born 1906 - Died 1987" is clearly not there in the wide shot, but instantly appears underneath his bio paragraph in the close-up shot; possibly because they didn't to reveal that he died until the close-up shot.
When Dottie initially quits the team, she tells Jimmy that she and her husband are driving back to Oregon. However, gasoline was rationed during the war and prominently displayed on their windshield is an "A" sticker, which entitled the holder to 4 gallons of gas per week. Dottie later says that they drove as far as Yellowstone National Park and turned around. They would never have been able to purchase enough gas to get from Rockford to Yellowstone and back.