Continuity mistake: After Mike and Ned fight with lightsabers, when they are in the kitchen Mike's wedding ring moves from his left hand to his right hand and back again, depending on the angle of the shot. (00:21:05)
Factual error: At the start in 1989, when Mike is dancing with the cheerleaders and also just before he goes after Scarlet, in close-ups of the crowd cheering there is a man (with a white baseball cap) wearing a Paramore t-shirt. However, Paramore (a Grammy-nominated American pop rock band) formed in 2004. The style of t-shirt he is wearing is actually one of the officially licensed Paramore merchandise. (00:02:45)
Continuity mistake: In the shot just after "Mark" tells Scarlet about Alex and the new girlfriend, Nicole (at the victory party), we see Jane's car driving down the block (towards the camera) headed to Ned's home and there are multiple black tire tracks (burned rubber) on the road at the intersection. After a close-up of Jane and Ned in the car discussing 'Halo', it cuts back to the intersection as the teenagers cut them off, and the tire tracks are gone. (01:16:50)
Continuity mistake: Before the '89 basketball game begins, Mike is on the court with the cheerleaders and when he pulls off his blue snap warm-up pants he is wearing the grey uniform shorts and jersey. However, after Mike poses in the close-up, he is wearing the blue warm-up pants again in the next shot from behind the cheerleaders - note his jersey number "0", which is visible between the cheerleaders. (00:03:05)
Visible crew/equipment: When Mike slams Stan down to the floor in Health class, the grey padded protective gear that Mike wears under his pants is visible as his shirt moves up. (00:47:25)
Continuity mistake: After Ned and Jane arrive at his house, they walk toward the kitchen as he shouts, "Everyboby out!" and in the shot from behind Ned is to Jane's right then moves to her left. However, in the next shot facing them, Ned is once again on Jane's right. (01:17:35)
Visible crew/equipment: Before the start of the last basketball game, when Ned calls out, "Jane!" for the third time in the shot facing him as he tries to pass someone, the actors' green T-mark and three other tape marks - one yellow and two red - are visible on the floor ahead of Ned. (Visible on DVD fullscreen.) (01:29:40)
Visible crew/equipment: When Mike satiates his hunger in Ned's kitchen, just after Ned says, "That's your can now, we'll label it like that," the reflection of a crewmember moving around is visible in the cabinet's glass pane, to the left of the screen. In the other shots of the same angle we don't see movement, so we know it's not Mike's reflection. (00:40:35)
Continuity mistake: After their fight, when Mike and Ned are in Ned's kitchen with frozen veggie 'ice-packs' over their assorted injuries, Mike has a bag of frozen peas that keeps turning around, facing the opposite way, repeatedly. (00:21:00)
Continuity mistake: At the restaurant, after Ned does his wine tasting, when the waiter pours wine into Jane's glass he holds the bottle in his left hand, as his right hand holds the cloth napkin, then lifts the bottle away from the glass when he is done. Next shot as he still pours wine in Jane's glass, the wine bottle is now in his right hand as he holds the base of the bottle with his left hand. (01:11:35)
Continuity mistake: On the bridge, when Mike topples into the water headfirst, the distinctive treads on the heels/soles of his shoes, as well as the light colored brand logo on the heels, are visible. After the newly transformed Mike appears at Ned's home wearing the same clothing, when Ned pulls the rug out from under Mike, his shoes' soles are completely different. (00:17:40 - 00:19:05)
Continuity mistake: After Naomi and Scarlet head into the house to work on getting Scarlet back on the market, when Mike is driving in the rain the rearview mirror is gone, but it reappears when Mike runs toward the 'janitor' who disappeared from the bridge. (00:16:45)
Continuity mistake: The morning after Mike's party at Ned's house, when Ned finishes vacuuming the rug in the overhead shot the wood floor immediately surrounding the rug is clean, but in the next shot there is a mess right beside the rug, which would have been visible in the previous shot had it been there. (01:20:25)
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 Ned and Mike encounter the street guard, whilst in the yellow car rushing to the court, the rear-view mirror changes position. (01:25:45)
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: When Maggie is crying, at one point Mike puts his arms around her. In the next shot his hand is on his head. (01:09:00)
Continuity mistake: During Mike's first class (before Maggie walks in), when he's on the cell with Scarlet, who is asking where he is, a cheerleader sits down behind Mike and places her right arm up with her hand at her chin and her left arm is down. However, in the next shot when she asks Mike if he would consider a 10th grader, now it's her left arm that is up and her right arm is down, instantly. (00:32:35)
Visible crew/equipment: When Mike is in the bathroom (before he sees Alex taped up) on the cell with Ned, in Ned's two close-ups the reflection of equipment moving (likely the boom) is visible behind him between his head and feet, as he lies on the couch. (00:34:50)
Continuity mistake: When Mike is talking to the basketball coach right before the team photo back in the 80's, Mike passes a basketball to the coach. There is then a shot of the coach and Mike reaches for the towel on his shoulder, then the shot switches to Mike and he reaches for the towel a second time. (00:01:10)
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