Continuity mistake: Due to the effect of the red glow on Kramer's eyes, he confuses the pitcher of tomato juice from Jerry's refrigerator for a pitcher of milk, pours it into the cereal, then gags and promptly tosses the contents of the bowl into the trash beside the fridge. In the close-up he tries to wipe some of it off the wall, but there's still a huge red mess left on the wall, in the trash, etc. In the next wide shot of Jerry and Kramer, the trash and wall are spotless.
Continuity mistake: George has constructed a model of the boardroom when his briefcase was destroyed. Jerry thinks George should be represented by the Yellow M&M figure. When the camera shows a close up of the figure, Jerry is holding it in a different position than the far away shots.
The Calzone - S7-E20
Factual error: When Jerry gets a speeding ticket, he asks Nicki to give the officer the registration. She gets a large piece of white paper from the glove compartment. That's what car registrations look like in California, where the show was produced. In New York, where it's supposed to take place, car registrations are the size of a driver's license, and are usually kept in the driver's wallet.
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.
Revealing mistake: When Kramer at the start of the episode puts the hose on the kitchen tap, he jerks the hose as it's not long enough to reach The Fire. If you look at the sink when Kramer does this, it comes easily out of its position on the counter top.
Continuity mistake: When they initially pull into the handicapped parking space, George is driving a large yellow Cadillac. When they return to see the car destroyed, it is now a much smaller blue car.
Continuity mistake: In the final scene where Newman is going to eat the bag of muffin stumps, Newman removes the bottles of milk and then takes a bite out of his muffin. He then takes a drink from the glass but he never filled the glass with milk in the first place.
Continuity mistake: In one scene George is solving a Rubik's cube in Jerry's apartment. When he leaves, he places the cube on Jerry's kitchen counter, and it is in the middle of the counter with the red color facing out. In the very next shot, it is moved much closer to the far edge of the counter and the color facing out has changed.
Factual error: The Devils-Rangers game is at Madison Square Garden, but when the Devils score, a siren goes off. That would only occur in the event of a Rangers goal.
Factual error: In this episode, after accepting a free Armani suit from Kenny Bania, Bania insists that Jerry repay him by taking him to a nice restaurant. Jerry takes Bania to Mendy's, a Glatt kosher NYC deli. During the ordering process Bania suggests, "Oh, get the swordfish. Best swordfish in the city. The best, Jerry." Swordfish is considered an unkosher fish by Glatt kosher standards since it does not have scales, one of the essential criteria. It would therefore never be served at Mendy's.
Continuity mistake: When Newman is first eating the chicken in Seinfeld's apartment, the amount of meat on the leg changes without Newman putting down the leg and getting another one out of the box.
The Bottle Deposit (1) - S7-E21
Character mistake: When Jerry tells Kramer and Newman that they left their groceries under the hood of his car, he comments, "The AAA guy said I was this close to sucking a muffin down the carburetor." Jerry's car is a Saab 9000, which are fuel injected.
Continuity mistake: While Kramer is explaining about being in the Woody Allen movie, George is in the background looking out the window trying to stop car alarms with his keys. Less then five seconds later, George ends up by Jerry's counter (without being seen) and has a can of Shasta in his hand. (00:08:40)
The Checks - S8-E7
Continuity mistake: When Jerry is showing George how he twirls the umbrella in his apartment, it has distinctive bright red and yellow stripes. He sets it on The Couch and then Kramer accidentally sits on it. It is now dark colored.
Continuity mistake: We find out George's parents sleep in separate beds. His father says "Thirty years ago we came to an agreement. It was the only way I could get some rest. Estelle's got The Jimmy arms." This contradicts S5E10, "The Cigar Store Indian", when George's parents come back from their trip, Estelle finds a condom wrapper in "our bed." Also Frank asks George, "You were having sex on our bed?", and Estelle follows by saying, "Who told you you could have sex in our bed?!" (00:16:50)
The Letter - S3-E21
Continuity mistake: While George is talking to Nina about the painting, Jerry can be seen taking a bottle of water from the refrigerator. He's then seen holding the bottle when buzzing up Elaine, but then when talking to Nina about the "pop-in", the bottle's gone. It's then back in the next shot when Nina says she's leaving. (00:15:13 - 00:16:00)
Visible crew/equipment: In the final scene with Larry David guiding Noreen off the bridge, a crew member's arm is visible in the bottom right corner of the screen. (00:22:30)
Deliberate mistake: When George is watching Home Alone, the sound effects and music that are heard aren't actually in the film.
Continuity mistake: When George shoos away everyone from The Apartment to make the phone call, in the background you can see the pink bottle with its black lid. When he actually approaches the phone, the bottle is uncapped. (00:09:35)
The Jacket - S2-E3
Continuity mistake: Jerry asks George in front of the fridge "You don't know Robert Schumann?"; between shots his shirt's collar is suddenly fixed, as earlier it was leaving the tie hanging out at the back. (00:05:50)
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