Poppy's By the Tree (1) - S2-E1
Continuity mistake: Bud asks to go down to the high school "tomorrow" to meet the man who met Andy Griffith. Earlier Al reads the events page in newspaper. The event was said to be "tonight."
Poppy's By the Tree (1) - S2-E1
Continuity mistake: When Kelly walks over to the table, she burps. She breaks character by laughing with her head down yet a second later, she has a serious look on her face.
Girls Just Want to Have Fun (1) - S2-E5
Continuity mistake: When we first see Peg and her friends at the kitchen table the fridge door is closed. Steve comes in with flowers and the door is open. He goes into the kitchen and it's closed.
Girls Just Want to Have Fun (1) - S2-E5
Continuity mistake: Al is having his fridge repaired. He goes and gets a beer and closes the door. A few shots later the door is wide open without anyone going near it.
Girls Just Want to Have Fun (2) - S2-E6
Continuity mistake: When sitting on sofa with Marci, Peg's necklace falls beneath her red blouse. It remains under in most shots, but in the last shot it is outside her shirt.
Continuity mistake: Marcy tells Peg that Steve has been gone for 5 days. Yet when he gets home, he has grown a full beard. It would take longer than 5 days to grow a full beard like that.
Build a Better Mousetrap - S2-E15
Continuity mistake: When Al hits his thumb with the hammer when trying to hit the mouse in the wall, he hits his left thumb. In the very next scene, Peggy is wrapping up his right thumb.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.