Continuity mistake: The bite size of the cookie that Jerry is eating changes between shots, without him even taking another bite. Not to mention the white and black change sides.
The Cigar Store Indian - S5-E10
Continuity mistake: George has sex in his parent's bed, explaining "My bed is too small." But in another episode, we see George's parents bedroom, and they sleep in separate twin beds, not a big bed.
Continuity mistake: In the episode where Kramer becomes a ball-man, the episode ends with them at a tennis match. It shows a shot of the court, and no one is standing anywhere near the poles of the net. In the next shot, Kramer is crouched down next to the pole, ready to dive for the ball.
Continuity mistake: When Jerry and Elaine are in the kitchen talking about circumcision, in some shots there is cereal on Jerry's spoon, and in some shots there isn't.
Continuity mistake: When Jerry is eating the black and white cookie in the bakery, sometimes the vanilla side is on the left and sometimes it is on the right. It keeps switching between shots.
Continuity mistake: At the end of the episode, Kramer is telling Olive that he met someone else. Olive says "who is she?" and she puts her hand on her hip, in the next shot both of her hands are back on the counter.
Continuity mistake: When Kramer is on the Regis and Kathie Lee show, after he puts up the cofee table, Kathie Lee has her coffee mug in her hand. In the next shot, her hands are empty, and in the next shot it's back in her hand again.
Continuity mistake: When Elaine and Jerry are confronting Testicoff about paying for the woman's hospital bill, in the view from behind Testicoff he puts his left hand down to scratch his pants. When the shot switches to a closeup of Testicoff, he is waving both arms above his head.
Continuity mistake: In the episode with Courtney Cox, when she and Jerry are arguing over a can opener, a bottle of beer keeps changing positions whenever they cut back to Jerry.
Continuity mistake: When George goes into the suit shop after being told about the sale, he sees another man trying on the suit. George tells the man the sale is on Monday and the man takes off the suit coat and George is holding it in his hands when the saleswoman says the sale is on Friday. In the next shot, she has the coat and is hanging it despite never taking it from George.
Continuity mistake: When Jerry opens the magazine to the article about him before handing it to George, the left side is mostly black with a picture and the right side is half black with "now" in big yellow letters. In the next shot of him handing the magazine to George, the page seen is mostly white with fine print and a small picture. In the next shots of George reading it, the magazine is back to where Jerry had opened it up to the first time.
The Glasses - S5-E3
Continuity mistake: When George bites into the onion, you can see the top of the onion is facing up or towards the camera, next to his finger. In the next shot, you can tell the onion has rotated position. You can see the root is to the side, so the top would be on the side instead of up.
Continuity mistake: When the man from the hand modeling agency is talking to George about Ray, he lifts up his right arm to make a claw with his hand, and as he does so he has his left arm holding up his right. After a cut, the man's left arm is suddenly hanging down, no longer supporting the other arm. (00:16:05)
Continuity mistake: While George is telling the whale story in the coffee shop, the ketchup bottle on the table disappears and reappears between shots. (00:19:00)
Continuity mistake: When Kramer is talking with Elaine and her coworker in the publishing office, his cigar appears and disappears between shots, as well as switches from his hand to his mouth in others, and from lit to not lit in others. (00:01:05)
Continuity mistake: When George is with his girlfriend at the coffee shop, the ketchup bottle on the table switches between being knocked over and stood up in different shots, despite nobody ever touching it. (00:03:10)
Continuity mistake: When Elaine is on the phone in Jerry's apartment, she holds the phone with one hand and lets the phone cord hang straight in one shot, and in the next shot she has the cord bunched up in her hand. (00:00:50)
Answer: Composer Jonathan Wolff used a synthesizer, although in seasons 7-9, a real bass is used in addition. Wolff also recorded himself making hundreds of mouth noises, pops, and slaps to add to the synthesized bass licks so that each episode has a different theme. The only real "back-story" is Jerry Seinfeld was having trouble coming up with a theme song and talked to a friend who happened to know Wolff. They wanted to avoid that cheesy late 80's sit-com theme song and Wolff came up with what we enjoy now. Jonathan Wolff has also talked about this further in interviews, recently Reed Dunela interviewed him, so for a fuller account of his story; check out "The Wolff of 116th street".
Bishop73