Visible crew/equipment: A boom mic is visible as Cliff gets off the couch and says "I know one thing, they are not going to live here."
Character mistake: Elvin has to sit on a stool at the dining room table and remarks that they are all out of chairs. But when Clair and Vanessa go into the kitchen to talk, there is an empty chair sitting by the kitchen table.
Pam Applies to College - S8-E4
Visible crew/equipment: If you look carefully, at the very top of the screen, during the scene where Olivia is telling the Huxtables that she didn't get to do her show-and-tell at school, you can see the microphone appear very briefly.
It's Apparent to Everyone - S8-E6
Continuity mistake: When Russell and Olivia leave, a stuffed animal appears on the table by the truck. When Clair comes in the stuffed animal disappears.
Continuity mistake: Clair comes into the kitchen and puts some bags on a chair. The next time they are seen they have changed position.
For Men Only - S8-E9
Factual error: When Olivia (or whoever) is teaching Russell how to play the Nintendo game she tells him the controls and includes "C and D". The old Nintendo system had no C or D.
For Men Only - S8-E9
Continuity mistake: When Russell is teaching Olivia and her friend how to play "pick up sticks," part way through the sticks at the end of the table close to Olivia disappear.
Continuity mistake: When Vanessa and Dabnis are talking, Vanessa sits down and takes off her coat - it falls down behind her. For the rest of the scene the coat appears and disappears on the chair behind her.
Continuity mistake: At the end of this episode, when Clarie enters the kitchen and closes the doors behind her, they are left a bit open. They remain open while Vanessa and Dabnis also enter the kitchen to say goodbye. When they leave and Clarie asks Cliff something, the doors are now completely closed.
Eat, Drink and Be Wary - S8-E16
Continuity mistake: This episode was obviously filmed before the kitchen was re done, but was aired after that.
Continuity mistake: Rudy takes the coat from one of the kids and puts it on the back of the chair Cliff is sitting on, at one point it falls off, it then reappears behind him, then moves to the table next to him.
Character mistake: When Dabnis and Vanessa first enter, Vanessa can be heard saying. "Hi, Grandpa. Hi, Rudy," when she is greeting Grandpa and Olivia.
Continuity mistake: At the beginning of the episode Cliff starts to cut up the sleepover treat, a couple of shots later Olivia's friend says "I knew we should have done this upstairs" - it is now uncut and Cliff starts cutting it again.
You Can't Stop the Music - S8-E22
Revealing mistake: Glue can be seen on Kenny's forehead after the carrot has been removed.
Some Gifts Aren't Deductible - S8-E23
Revealing mistake: When Stanley comes into the kitchen he has three demands, on paper from Deirdre, to which Kenny must agree. After Stanley reads the demands, Kenny signs it. You can plainly see that the paper is blank the moment after he signs it and gives it back to Stanley.
And So We Commence (1) - S8-E24
Plot hole: When Theo is complaining that his father is inviting too many people to his graduation, he says "I saw him in the backyard 5 minutes ago hosing down the beach chairs", but this couldn't have been possible because in fact, Cliff was upstairs right before that scene, and then went straight to the living room, so there's no possible way that Cliff could have been in the yard at the time Theo had said he was.
Chosen answer: That is the song "Open the Door Richard."