The "wet spot" that Poppie leaves behind on Jerry's new couch, is actually there before Reni Santoni even sits down, hidden by newspapers. As he sits, at the last moment, he slips the newspapers aside, so that when he stands up again, the wet spot is visible.
George goes out of his way to avoid reading Breakfast at Tiffany's (and in Season 8's "The Fatigues", a book on anger management), however in Season 5's "The Conversion", he talks about how easy it is to become a Latvian Orthodox: "All I have to do is read a few books…." What's more, the "few books" he must read are thick, ancient religious texts.
Elaine says that she loves eating duck, but in The Strike, we learned that the only meat she will eat is fish occasionally.
George: If it's not about sports, I find it very hard to concentrate.
Jerry: You're not very bright, are you?
George: No I'm not. I would like to be, but I'm not.
Jerry: (admiring his new sofa) What do you think Lainey?
Elaine: Well, I don't know. I'll have to sit on it.
Jerry: Oh no. I don't want anyone sitting on it.
George: (to Jerry) I got a feeling I'm going to be much smarter than you pretty soon.
Jerry: Poppie peed on my sofa!
George: You know what I love? How there's two nuts named after people: Hazel and Filbert.
Jerry: (on Elaine's boyfriend) What is his stand...on abortion?
Elaine: Well, I'm sure he's pro-choice.
Jerry: How do you know?
Elaine: Because he, well...he's just so good-looking.