Continuity mistake: During the scene where Dottie and Jimmy are sitting beside each other at the front of the bus having a conversation, the camera cuts to Mae painting Kit's nails on the back seat of the bus. When the camera cuts back to Dottie and Jimmy, if you look at the back seat of the bus, Mae is sitting by herself and Kit is already about to sit back down in her seat in the middle of the bus. It doesn't seem likely that there would have been enough time for her to be in that position so quickly.
Continuity mistake: During the tryout/league formation sequence at Harvey (Wrigley) Field, every shot takes place at the famous stadium, except one. When Betty Spaghetti backpedals to catch a fly ball, the background shows a rickety wooden outfield fence, not Wrigley's famous ivy-covered walls.
Continuity mistake: A very early 1943 scene in Oregon shows baseball scout Jon Lovitz waiting in the club car of a train with a steam engine complete with smokestack. Geena Davis and Lori Petty run to catch the train for tryouts. But after they board in the next scene, the steam locomotive has disappeared and now a modern diesel engine is in front of the train heading east to Fort Collins, Colorado.
Factual error: In the final game when Kit comes to bat, we get a quick glimpse of the right field foul line and there is an umpire standing on the line behind first base. In a previous shot, we see an umpire standing on the left field foul line behind third base. In the 1940s, three umpires were used for the majority of the games. With a runner on first base, as is the situation here, the umpire would position himself between first and second base. During the shots of Kit running the bases after she hit the ball, we see no other umpire between first and second base or anywhere near second base.
Revealing mistake: In the scene at the church, immediately after the girls were at the Suds Bucket, Mae is in the confessional when the priest drops his Bible. Mae steps out and kneels to pray as the priest opens the door to see who has just made their confessions. A closeup of the priest's face reveals that he has a "cowlick" (several locks of hair) hanging down in the middle of his forehead, but in the very next shot showing him in the background looking down at Mae, the lock of hair is suddenly gone.
Continuity mistake: After the final game we see the girls leaving the changing room, but Dotty is still there. The last two girls are about to leave, and we see Dotty about to put her tights on. She has not started putting them on, but then the shot changes and she is already rolling them up her legs.
Continuity mistake: During the music clip, when Jimmy is finally starting to take over the managerial duties of the team, there is a scene where he is instructing Beverly before batting. We see the very same spectators sitting behind the Rockford bench, who were there in the other scene where Jimmy and Dottie were concurrently instructing Marla before batting - which happened several games before.