Continuity mistake: After Cliff talks to Peter, Theo is told to run to the neighbors across the street. However, he can be seen in the background of some shots when the twins do their game. As soon as the twins finish, Theo is shown coming back into the house.
Continuity mistake: In this episode, Rudy is riding her bike around the house which is right on the corner of a block. Since when is their house on the corner?
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: Cliff says "a young trumpet player while sitting in the bandstand watching the dancers". But in all the later episodes, Russell plays the trombone, and he had been for a long time.
Continuity mistake: When Cliff returns from the store for about the fourth time and the eggs and tomatoes fall out of wet bag onto the floor why aren't the eggs in a carton? The bottom of the bag drops out, so the carton can't be in the bag.
Continuity mistake: When Pam is in the office talking to Cliff and he tells her about the curfew time, she has a pencil in her hand and a pad in her lap. In the next shot, Cliff offers her a pencil and tells her to take the pad (which is on his desk).
Denise Kendall: Babysitter - S6-E6
Continuity mistake: In the scene where Bob gives Elvin the apple cider and another jar, when you first see the two jars, the jar in his left hand has a few inches of foam on the top. Bob sets the jars on the table, and the foam is gone. When the shot returns to the table the foam is back again.
Continuity mistake: The father was known as Clifford in the beginning but the name was changed to Heathcliff (you can see this on the nameplate for his office).
War Stories - S3-E11
Continuity mistake: Towards the end of the episode, Cliff Huxtable is sitting in the living room with his father Russell, Sgt. Stokes, and Homer. He is telling them of an incident that happened while he was in Bermuda. He is using dominoes to explain his story. At first there are about six or seven dominoes standing up on their sides. The camera angle switches, and all the dominoes are flat on the table. It goes on for a minute or so with the dominoes lying flat on the table. Then when Russell, Sgt. Stokes, and Homer get up to go for a walk, the dominoes are standing up again.
Mr. Fish (a.k.a. Goodbye, Mr. Fish) - S1-E2
Continuity mistake: While some of the family is eating, the cup in front of Denise disappears than reappears.
Continuity mistake: In the scene where Theo tries to prank Cliff, and Theo grabs the fake gum, he stuffs the "Bag 'o' Gags" under his shirt. You can see throughout the scene that Theo is holding up the bag with his hand. Later on in this scene, the bag drops. In the next shot, there is something green showing from underneath Theo's shirt (The Bag 'o' Gags). Then in the next shot it is hidden again, being held up by Theo's hand. (00:03:55 - 00:05:55)
Mrs. Huxtable Goes to Kindergarten - S5-E14
Continuity mistake: In the previous episode they got a new couch, in this episode the old one is back.
Continuity mistake: At the end of the episode, Theo and Cliff are drinking a soda. Cliff pours half of his in a glass and begins drinking it. When the camera pans for the end of the episode, the bottle that cliff set down is once again full.
Breaking With Tradition - S1-E6
Continuity mistake: Theo and Cliff walk into the kitchen and Cliff sets the basketball on the counter. Theo walks upstairs. When the camera is back on the counter the basketball is gone.
Continuity mistake: When Vanessa walks down the steps and drops all her papers, they are shown on the steps, then off the steps and then on again.
Continuity mistake: After Theo gives up an extra $100 for clothes, he is holding $300 left in his hand. However when the camera switches back to Cliff, who asks how much is left, it switches back to Theo, who is only holding $200 left.
Continuity mistake: Cliff and Clair are talking in the living room while Cliff is making a sandwich. As Clair asks Cliff if he would trust her with a sexy man, Cliff starts putting potato chips on his sandwich from a bowl. As he takes the chips out of the bowl, the level of chips goes down. When Cliff asks Clair if she would trust him with a nineteen year old woman, the bowl is miraculously at the level it was at the beginning of the scene. But as Cliff finishes talking, the bowl is back to it previous level.
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.
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.
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.
Chosen answer: That is the song "Open the Door Richard."