Continuity mistake: When young Al reaches forward with his left arm to take the book that Miss Degroot wants to give to him, she quickly pulls back but young AL still has his arm raised. In the next shot, his hand his down by his side.
The Bald and the Beautiful - S3-E7
Other mistake: At the end of this episode, there is a typo in the credits: "Directed by" is written twice. (00:22:30)
Can't Dance, Don't Ask Me (aka Kelly's Dance) - S3-E13
Continuity mistake: During Kelly's dance, a nerdy girl grabs Bud and starts kissing him, but in the next shot, Bud is standing alone in the background. (00:20:30)
Can't Dance, Don't Ask Me (aka Kelly's Dance) - S3-E13
Continuity mistake: While Kelly is dancing with the guy at school, a nerd girl starts kissing on Bud and pushes him backwards. The very next second when the scene changes, Bud on the left side is back playing the record for the music without anyone around him.
The House That Peg Lost - S3-E16
Plot hole: Marcy and Steve live on the left-hand side of Al and Peg yet when they come home and see their house is gone Peg is looking out the window in the front door saying they're looking at the hole now they're looking over here.
Revealing mistake: At the start of the episode, Peg is making popcorn on the stove. It's making a sizzling sound like she's really popping it but the burner isn't even on.
Eatin' Out - S3-E11
Revealing mistake: At the end of this episode, Bud supposedly has a lemon frozen to his mouth but he plainly is just biting down on it. Then Al uses his lighter to "unstick" it, but Bud just spits it out.
Revealing mistake: Peg is making popcorn on the stove. It pops even though the burner isn't even on.
I'll See You in Court - S3-E10
Continuity mistake: While they are in court, Steve is talking about the case and the clock says 12:30. Next time he's seen and talking about privacy to the jury, the clock says 11:30. Then when done talking, the clock says 3:00. The very next scene as the court proceedings are going forward, now the clock says 12:29. Next scene says 4:32. Than backwards again. The clock is moving forward and backwards throughout the entire scene.
Other mistake: Al, Peg, and the kids go to the beach. Steve and Marcy are sitting not too far away from them, yet they never interact with each other. They had to see each other they just act like they don't notice each other.
Revealing mistake: When Bud is at the shoe store with Al, right after Bid says something about the woman with chicken wings, you see the flash from a camera.
The Bald and the Beautiful - S3-E7
Other mistake: Al and Steve are using Dr fur for growing hair. After using it, Steve says it was recalled. Later in the show, Peg says she is going to the store to buy Dr Fur because it was the only thing that Buck would eat. If it was recalled it wouldn't be available to buy anymore in the store.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.