Continuity mistake: In episode 64, "For Whom The Bell Tolls. And Tolls. And Tolls", Tracy is shown seated at the table with a bowl of cereal - but in the shots immediately before and after, she's not there, nor is there any food at her place. (00:01:10)
Continuity mistake: In an episode fairly late in the life of the show, Lou Grant says that when Mary came to interview for a job at the station, she bumped into the desk in his office and said, "Excuse me" to the inanimate object. However, we saw that interview in the very first episode, and no such thing happened.
Kitten Kong - S2-E7
Continuity mistake: Just after Bill puts a duck in the basket of looney animals, all these grey feathers come pouring out. But, the duck hasn't got any grey feathers, and there was nothing in the basket that had any.
Continuity mistake: When the gang first arrive at the stately home Albert parks his car next to a coach. When the camera angle changes the car has moved back a few yards, and when the gang leave the car has changed position completely.
Continuity mistake: In the opening credits of the first season of The Odd Couple, Felix is moving in "with his childhood friend", Oscar. In a subsequent season, a storyline does a flashback to say that Felix and Oscar met when they were both jurors at a trial. Soon after, they cut the word "childhood" on most of the openings after people called the station to mention the mistake.