Continuity mistake: When George and Susan are arguing over dinner about her cousin stealing the name Seven, Susan holds her glass up to her mouth in one shot. In the very next shot, the glass is on the table.
Continuity mistake: When George is at Susan's cousins' house complaining about them stealing the name Seven, its bright Daylight out. You can tell because the sun is pouring in through the windows. The woman goes into labor and they all get into the car to go to the hospital. At this point it is nighttime. When they finally arrive at the hospital it is broad daylight again.
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