Corrected entry: When Jerry and Elaine are trying to get on the plane, they are told that the plane is full except for two seats, one in first class and one in coach. However, Elaine is later able to find an empty seat in first class, but there were only two openings, when they boarded.
Corrected entry: Kramer walks into Jerry's apartment to get a Pepsi and tells Jerry that he would get Jerry's watch back (the one that Jerry threw away). Jerry then goes to Kramer's apartment door. When Kramer leaves Jerry's apartment, he has the Pepsi in his right hand. When Jerry tells Kramer that he had thrown away the watch, the Pepsi can is gone.
Corrected entry: In the episode where Jerry is going to the Superbowl, when he's going to sit down he says his seat is seat 4 and counts over to find his seat (and also to find Newman there). But the only empty seat in the row he's going down is the third seat. If his seat were the fourth, then Newman would have been sitting in his seat, so they both should be over one seat.
Corrected entry: I've always wondered how Kramer is able to live in a New York City/Manhattan apartment. The guy has no job, no prospects of getting a job, doesn't seem to have money in the bank (or at least enough of it to cover the costs of living in his apt) and yet can afford to live there. To the best of my knowledge it is never explained how he's able to afford it. [This is supposed to be one of the eternal mysteries of Kramer. In fact, Jerry and Elaine discuss how great it must be to be Kramer in one episode ("He meets all these beautiful women, he falls a**backwards into money...").]