Who Shot Mr. Burns? (1) - S6-E25
Revealing mistake: Right at the beginning, watch as Principle Skinner enters the classroom, there's a clock on the top left hand of the screen. The majority of the left side of the clock is not drawn in.

Who Shot Mr. Burns? (1) - S6-E25
Revealing mistake: Right at the beginning, watch as Principle Skinner enters the classroom, there's a clock on the top left hand of the screen. The majority of the left side of the clock is not drawn in.
Continuity mistake: When Homer's Vegas wife shows him the video in front of Marge, it shows Homer kissing Ned. This didn't happen when she showed it in the Vegas episode.
Skinner's Sense of Snow - S12-E8
Nelson: Hey, look how much Skinner makes: $25,000 a year.
Bart: Let's see, he's 40 years old times 25 grand. Whoa, he's a millionaire.
Skinner: I wasn't a principal when I was one.
Nelson: Plus, in the summer, he paints houses.
Milhouse: He's a billionaire.
Skinner: If I were a billionaire, why would I be living with my mother? [All the kids laugh at him.] They're just not responding to logic anymore.
Trivia: The only voice artists who regularly perform as only one character are Yeardley Smith as Lisa and Marcia Wallace as Edna Krabappel. Yeardley has also voiced different versions of Lisa (Lisa Jr. and Lisabella) in at least two other episodes.
Question: Which episodes feature the "Howling Dog" (usually used on outside shots of buildings)?