Continuity mistake: When Alex and Mike are seated for lunch in the school cafeteria, Mike's sunglasses hang on his t-shirt collar then appear on the table and continue to change position on the table, beside the food tray. (00:36:15)
Continuity mistake: In the school cafeteria, when Mike and Alex first sit at the table Mike and his tray are directly opposite Alex, but next shot they are seated diagonally to one another with Mike at the end of the table, then they're opposite each other again, and the tray's position still changes between camera angles in following shots. (00:36:20)
Continuity mistake: When Mike's talking to his son in the school cafeteria (just before his ridiculing of Stan, the bully) keep an eye on his burger - it's sometimes in his hand, sometimes not, and changes position in the box and tray as well. (00:36:30)
Continuity mistake: When Mike is eating the stick thing in Ned's kitchen, there is still wrapper on it that disappears when he is putting the cheese on it. (00:40:30)
Continuity mistake: After Naomi and Scarlet arrive home, when Alex introduces "Mark" to his mom, Scarlet holds her handbag in her left hand down by her side, then it's up on her raised forearm at the elbow and once again in her hand down at her side. (00:42:45)
Continuity mistake: When Mike walks into Health class, Mrs. Dell's lectern and stool (upon which the basket of condoms and another basket sit) stand directly in front of the chalkboard, but funny how they are both conveniently gone when Mike knocks Stan to the floor, in front of that chalkboard. (00:44:45 - 00:47:25)
Continuity mistake: Just as Mike walks to his seat in Health class, the skeleton stands in front of the window's blue shades, to the right. When Mike knocks Stan to the floor, the skeleton is right beside the classroom door. (00:44:50 - 00:47:30)
Continuity mistake: In Health class, when Mike begins explaining his views on abstinence, Mrs. Dell has her arms down in close-ups facing Maggie, but in the shots facing the class Mrs. Dell's arms are crossed in front of her. (00:46:15)
Continuity mistake: When Mike begins to voice his thoughts in Health class, as he says, "It's called 'making love', isn't it?" Maggie is holding the pencil up in her hands, but next shot the pencil is gone. (00:46:20)
Continuity mistake: During Health class, when Stan says, "Great, fine, wonderful! More for me," and dumps more condom packages on his desk, his pencil is to the left of his textbook, then next shot it's to the right of the book, and in the final shot when Mike slams into Stan the pencil is at the top edge of the book. (00:47:20)
Continuity mistake: The condoms an Stan's desk keep changing throughout the entire science class scene, especially when he says, "OK, fine, more for me." (00:47:25)
Continuity mistake: During Health class, when Mike knocks Stan to the floor Stan wears a baseball cap which falls off, but as Mrs. Dell shouts, "Boys, stop it!" the cap is back on Stan's head before it falls off again. (00:47:30)
Continuity mistake: After the fight with Stan, Mike gets sent to the principal's office. There is a poster behind him that says "Your Career For Life Is" and at the bottom, a star. In the first shot, the poster is above Mike's head, but then in the next shot, Mike's head is covering the star. (00:48:15)
Continuity mistake: When Ned walks into Principal Masterson's office and does the "peacocking" bit, in the close-up his index finger is at his chin as he holds his sunglasses by its arms dangling on his thumb, with the lenses facing down, but in the next shot the lenses are facing up between his fingers and his face. (00:49:05)
Continuity mistake: When Alex tells his mom that he made the team, as they hug his left arm is over her right arm, but in the next close-up Scarlet's arm is instantly over Alex's arm. (00:53:20)
Continuity mistake: When Scarlet dances face-to-face with Mike, her left hand moves from his shoulder to her side so as to move Mike's hand up on her back, but Scarlet's left hand goes back and forth instantly a couple of times, between shots. (00:56:15)
Continuity mistake: Before Scarlet's date arrives, during the dance when Mike spins her in his arms, in a few shots Scarlet's hands are atop one another on Mike's shoulder and her bracelet is at her wrist, but in-between those shots in one shot her hands are apart gripping his shoulder and her bracelet is up on her forearm. (00:56:45)
Continuity mistake: When Alex walks in on Mike dancing with Scarlet, in the background Alex's arm is out as he turns off the stereo with the remote and then puts his hands in his back pockets in close-up. Then two shots later, Alex's hand with the remote once again points to the stereo and then puts his hands by his back pockets. (00:56:55)
Continuity mistake: When Scarlet leaves with her date, Mike is holding her bouquet of flowers and the direction they face changes between the front and back shots - note the two tall purple Liatris flower heads. (00:58:30)
Continuity mistake: When Alex freaks at Mike for staring straight at the girl he has a crush on, he fully opens his eyes. They are normal in the next shot as he talks to Mike. (00:59:20)
Answer: I've not seen the movie, but an ex-wife would be closer to her ex-husband than a coach to his old student, no matter how good.
JonTheRandom