Plot hole: Al can't eat because his mouth is numb. So they go ahead and eat. Al can eat after the novocaine wears off and Peg can put leftovers in the fridge. They all act like Al can't eat for days and there won't be any food left.
He Ain't Much, But He's Mine - S4-E5
Plot hole: Marcy gets her hair done like Pegs. Everyone makes fun of her saying she looks ridiculous. All she has to do is wash it! Its obviously held up with hairspray but Marcy acts like there's nothing she can do about it.
You Gotta Know When to Fold 'Em (2) - S4-E17
Plot hole: Al hasn't got enough cash to pay for a pizza and Peggy overmaxes his credit cards. But somehow he manages to buy three flight tickets for Chicago-Las Vegas. Where'd the money come from? Also, when his card is declined, he calls the pizza shop back (they call him "no tip" Bundy), and somehow they know where Peggy maxed out the credit card. (00:05:15)
Plot hole: In this episode Al is about to break Puggy Weaver's record. Peg decides to bowl and scores a perfect score of 300. Problem is Peg is a horrible bowler, as seen in season 2 episode 9. She never bowls with Al or even enjoys bowling, so this episode really makes no sense.
Suggested correction: This is not a plot hole, but a plot point. Yes, Peg is a horrible bowler, but it's typical Al Bundy luck that his wife would be able to put together a perfect game no matter how unlikely.
So this one and only episode she scores a perfect game? Highly unlikely. Oh and she's wearing a long evening dress too which would make it difficult to bowl. So this episode makes no sense.
It makes perfect sense. In the world of the show, the universe is out to screw Al over. The worst that can possibly happen to him will happen no matter how unlikely.
It is a comedy, so having all those "strikes" against her, she still managed to bowl a perfect game - leaving Al hopeless and hapless.