Three Coaches & a Bobby - S3-E12
Continuity mistake: As Coach Sauers is making them run up and down the stands you can see Bobby with all the mud on his face and body just reaching the bottom of the stand and then in the very next shot hes all of a sudden reaching the top of the stands with Joseph. (00:08:35)
Three Coaches & a Bobby - S3-E12
Continuity mistake: As Coach Sauers is quitting the shoe store, he rips the whistle off his chest and breaks the neck rope and bangs it down on the counter. When the clerk returns the whistle to him and drops it in his hand, the rope is not broken, as you can see the loop on the rope when it drops. (00:06:50)
Three Coaches & a Bobby - S3-E12
Continuity mistake: Before Peggy leaves the soccer mums and goes to watch football again, the woman in the green sweater is holding a coffee cup that is of a pale brown color. When the shot goes to a close up of her talking, the color is now red. The next time you see her holding the cup, it's gone back to being a pale brown color. (00:18:15)
Three Coaches & a Bobby - S3-E12
Continuity mistake: The two women near Peggy, who are sitting on the benches in the stands, are seated on the fourth and fifth levels in the wideshots, but in the close-up they're seated on the third and fourth levels.
Three Coaches & a Bobby - S3-E12
Continuity mistake: When Coach Sauers is trying to run over the football players with his car on the football field, there are a lot of track marks on the field. There is then a tracking shot of Sauers from straight ahead of his car and you can see there are absolutely no track marks whatsoever, on the field behind him. (00:15:30)
Three Coaches & a Bobby - S3-E12
Continuity mistake: As the football team is meeting Coach Sauers for the first time, you can see the team from behind with Bobby kneeling and Joseph behind him to his right. However, when the shot shows the group from the front, Joseph is now to the left and some kid with brown hair to Bobby's right. (00:07:40)
Three Coaches & a Bobby - S3-E12
Factual error: Before Hank knocks Coach Sauers out with the drink case, the coach starts up his car, but when Hank knocks him out the engine turns off as soon as Hank hits him. The engine wouldn't turn off because of being unconscious. (00:16:20)
Three Coaches & a Bobby - S3-E12
Continuity mistake: When Hank sees Coach Sauer driving his car on the field, you can see Sauer's car has a red front bumper. When we see the front bumper again a few shots later it is grey. (00:15:30)
Three Coaches & a Bobby - S3-E12
Continuity mistake: If you look carefully during Coach Sauer's training run while Bobby is running down the stands, you will quickly see the mud disappear on Bobby's face and reappear in the next frame. (00:08:35)
Answer: In addition to Brian Katcher's response: it's supposed to be a joke that Dale is always suspicious about conspiracy theories, mysteries, etc, but he is "clueless" about his own wife having an affair. Of course, as Brian wrote, many fans think that Dale is pretending to be clueless because he doesn't want Nancy to leave him.