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 and Ned are in Principal Masterson's office and she says, "I think Hayden would be lucky to have you," she stands up and removes her eyeglasses, but when she shakes Mike's hand she is wearing the glasses, and next shot they're off again. Then yet again, when she sits back down she is wearing them (in the foreground), just before Ned asks, "Would the lady mind if I smelled it?" (00:28:50)
Continuity mistake: While Ned and Mike are waiting for the school secretary to get off the phone (for enrollment), when Mike opens the folder the faked science fair photo is at the top of the pile on the right. In the next shot, there is a photo on the left leaning on the inside of the folder cover and the science fair photo isn't at the top of the pile on the right, but when it cuts there are no photos on the folder cover. Then Mike closes the folder, but next shot it's open again. (00:26:10)
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 Ned and Mike are in Principal Masterson's office, as she reviews Mike's transcripts there are some open pages on her PC screen, but in her close-ups the screensaver is active, then it's back to the original screen. (00:28:20)
Continuity mistake: In the ice cream shop, after Alex tells Mike that Maggie got into Georgetown, in the side shot when Mike leans forward to pick up Maggie's earpiece wire he asks, "Can you turn down the...," but his mouth doesn't move, and then in the next shot he leans forward once again to pick up the wire. (00:13:05)
Continuity mistake: During Mike's slapfest, given by Scarlet, Maggie and her three friends, when the blonde slaps him she turns toward her left to walk away, but in the next shot facing Mike she turns to her right to walk away. Maggie did the same thing, but the opposite way. (01:19:10)
Continuity mistake: After Scarlet slaps "Mark" for kissing her, he runs after her trying to explain who he is, and when she stops him Scarlet either has her right hand up or her left hand up angrily pointing at him, depending on the angle of the shot. (01:18:55)
Continuity mistake: At the bowling alley, when Mike is with Maggie's three friends and speaks to the "too flexible" girl, her left hand is either on Mike's shoulder or not, depending on camera angle. (01:00:30)
Continuity mistake: When Alex and Mike are at the bowling alley, after Mike says, "Any girl in here would be lucky to have your attention," Alex's collar is either up behind his neck or lying flat in the following shots. (00:59:35)
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: 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 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: The position of the team (note Ned, court lines, etc), when the 1989 photograph is taken at the start, differs from the framed photo that Mike looks at when he meets the 'janitor' at Hayden High. (00:02:00)
Continuity mistake: During Ned and Principal Masterson's conversation at the restaurant, after Ned tells her, "I'm the kind of guy who spends ten grand on Gandalf the Grey's quarterstaff from The Two Towers," Principal Masterson's hands are clasped on the table in front of her, but in the next shot she is holding the menu up in front her. Next shot the menu is on the table, but then up in her hands once again. (01:12:05)
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: 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: In Mike's first class, when he sees Maggie walk in while on the cell with Scarlet, his left arm is either in front of him with his left hand up near his mouth, or his left elbow is on the desk with his head leaning on his left hand. The switch happens twice. (00:32:50)
Continuity mistake: After the 1989 scene is finished, we see adult Mike lying with his head on a pillow in a close-up. In the next shot Mike's head has now moved up higher on the pillow. (00:06:50)
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