Corrected entry: Kramer steps back out of the view of the camera as he opens his shirt, all in an attempt to show Jerry the mistake he's making by shaving his chest. Kramer laughably shouts "look at it!" repeatedly to Jerry, who recoils in disgust at the (supposed) sight of Kramer's thickly-haired chest. The problem is that Kramer's bare chest is shown in episodes before and after and there is nothing unusual about it. In fact, just two episodes later (in Season 9's "The Butter Shave"), there are multiple shots of Kramer's chest. Were we supposed to forget about this little occurrence in Jerry's apartment?
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...").]
Corrected entry: After Jerry talks to Joel for the first time on the phone, George asks "who is this guy?" I'm sure that if George and Jerry had grown up together and have been close friends for so long, he would have, at some point in time, heard about him, or even met him. Especially if he keeps calling Jerry and trying to create a friendship.
Corrected entry: Near the end of Elaine's conversation with Lippmann about The Muffin Tops in The Bookstore, there is a deep male voice that can be heard saying something unintelligible (it might be Kramer's voice), which must have been layered in the background by accident. (00:04:25)
Corrected entry: In this episode, George finds out that Sheila, the photo store woman, is checking out his pictures during development. Right after he discovers this, he goes to Jerry's apartment and starts snapping pictures, one of which is of Jerry fiddling with his stereo with a screwdriver. Later on in the episode, Newman passes by the photo place and happens to see that photo being developed, so he confiscates the roll (which also includes George's sexy photos). The problem is, the photo of Jerry could not have been on that roll since George had already been back to the photo place at least once before after snapping the picture of Jerry. Jerry's picture would've been in the roll that had the picture of the scantily-clad model and of George posing with the Mercedes.
Corrected entry: Throughout the whole show, George Costanza is showed as being left-handed (eg. at the beginning of the episode titled "The Shoes", Jerry and George are writing "The Butler" script, and George can clearly be seen writing with his left hand). However, the actor himself is not, and you can spot some episodes (mostly in the first seasons) but a few in the last seasons as well, with him using his right hand for writing or eating, while in most of the show he's using his left-hand for everything.
Corrected entry: At the very end of the episode, George tries to save Mr. Wilhelm from the Sunshine Carpet Cleaners cult. As soon as their dialogue ends, the male Japanese TV executive says to the female executive, "With these two idiots, I don't know how the Yankees won the World Series." How in the world does this guy know that George and Wilhelm are/were employed by the Yankees? It's possible George may have mentioned it upon meeting with the executives (off screen). But it's more than reasonable to assume that such a discussion never took place between the executives and Wilhelm, especially considering Wilhelm did not even seem to know about his past experiences due to being brainwashed.
Corrected entry: When Newman is helping Kramer talk to Pam in The Library, you can see (through the bookshelf) that Newman is mouthing the same words at the exact same time as Kramer. You would expect Newman to mouth some words, pause and Kramer would then repeat them to Pam.
Corrected entry: George's boss Kruger claims that the mole on his back hasn't changed in the past ten years from the picture on his desk. However the mole wouldn't be visible in the picture as you cannot see Kruger's back in the picture. Kruger is facing chest forward in the picture.