When Jerry (Jerry Seinfeld) and George (Jason Alexander) are walking down the stairway talking about Red China, they are walking side by side. In the nest shot after they round the corner, they have switched places.
In the final scene, when Kramer (Michael Richards) gets out of the car & looks into the distance was completely improvised, and it's possible to see the other actors starting to laugh at the end of the take.
Kramer struggles to put the box with his air conditioner into the trunk, which resulted in him slamming the box into the trunk hard. Michael Richards injured himself, banging his lip on the box's corner and cutting it open. The other cast members broke into genuine laughter while Richards himself managed to stay in character. He looked at Julia Louis-Dreyfus and said "I really hurt myself, Elaine."