At around 17 minutes, Kramer enters Jerry's apartment just as the air conditioner begins to fall from the window. As Kramer attempts to save the air conditioner, he bumps into the desk table, jostling everything on it. The computer monitor ends up turned toward the wall. When the air conditioner is shown falling from outside the apartment, through the window you can see the undisturbed monitor and computer.
As Kramer is exiting Jerry"s apartment and George is entering, Kramer's right hand only is in his pant pocket but when the camera shot changes both hands are in his pant pockets.
When George takes the onion out of the refrigerator he closes the door the following scene the fridge can be seen with the door open.
The orange that Elaine is slowly peeling goes from about one-third peeled to completely peeled in a matter of seconds between cuts.
When Elaine is bitten by the dog a box of tissues mysteriously appear at her feet.
In the opening scene when Elaine and Jerry are looking out of his apartment's window you can see that it is dark in his kitchen but when they turn around to talk to Kramer, the lights are back on.