Continuity mistake: After Joe picks his daughter up from her mother's, they drive into Minneapolis. While Joe is talking to his daughter, you can see Macaroni Grill and Galyns out the window as they drive past. After a quick shot of the daughter, when the camera is back on Joe, if you look out the car window again, they are passing the same establishments.
Audio problem: When Joe is helping Meg with hanging the banner in the cafeteria, there is a table with coffee mugs stacked in a pyramid shape. As the banner crashes to the floor, you hear the mugs breaking. As the camera shows the full banner finally hung up, the coffee cups are still on the table in the same position.
Continuity mistake: In the scene where Meg goes to Joe's house for the second time, you see her pull up in a red Jimmy SUV. Pay attention to the wheels. After the scene in the school yard with about five minutes left in the movie, Joe is parked in Meg's space. She pulls up in the same Jimmy, but with different wheels.