When Jerry and George talk about Gary in the apartment, Jerry takes one water bottle out of the fridge. When Elaine comes over a second bottle appears on the counter out of nowhere, disappears, then reappears.
When George tells Jerry about Gary's surgery, he holds his glasses loosely at his side. In the next shot he has them almost completely on.
As Kramer talks to the cop, a woman in a red hat passes from the right to the left twice.
When the cop finds the "white whale" the car is empty, but suddenly Newman (Wayne Knight) is it when George (Jason Alexander) hits it.
Newman's car is stated to be a 1979 Dodge Diplomat. The car used is clearly a 1986 model year, evidenced by the centre high mount brake light.
At around the 16:30 mark, when Kramer jumps into Newman's car and says "Just drive", the stock footage behind them changes and a white car appears out of nowhere.
Background footage is reused (for the close-ups, not the back window) in the second car scene with George and Debby. They're passing the same cars and people as in the first scene a few minutes earlier.
At about the 5:00 mark, when Kramer and the cop are talking, in the window reflection behind the cop, extras are visible waiting in line and receiving direction on when to start walking past the two.
When Kramer is explaining to the policeman that he was yelling at somebody else, the boom mic is shortly visible on the top right.