The lower right portion of the screen in the scene where Kramer (Michael Richards) gives a tour of Central Park is reused in the scene immediately after.
When Kramer falls outside his apartment and drops his groceries the cans of Coke from the trays are all scattered. In the next shot there is an intact tray of cans on the floor.
When Jerry throws the rye to the third floor the exterior shot shows the second floor window curtains are closed. The next shot is the interior of the second floor window and the curtains are open showing the couple's reaction.
As the Rosses board the carriage, the blanket is bunched up behind the driver's seat. It then cuts to Kramer saying "Happy anniversary", then back to the Rosses, and the blanket is now spread neatly over their knees.
Kramer lands on his back when he drops the groceries. When the old man comes to assist, he gets up as though he'd landed on his front. Also, the two cereal boxes land in one place and have noticeably moved as Kramer gets up.
The horse-drawn carriage is referred to a number of times as a "hansom cab," when it clearly is not- hansom cabs have two wheels and the driver sits behind the passengers, while this carriage has four wheels and the driver up front. Even the owner of the carriage, who should know better, calls it this. (In addition, it is not strictly speaking a "cab," as it is not a taxi, but this is common usage.)
The woman in the bakery that they were out of marble ryes, when there are clearly several more on the shelf behind her.
While Jerry (Jerry Seinfeld) is trying to throw the rye up to George (Jason Alexander), George tells him Susan (Heidi Swedberg) won't be home until 8pm. When George does get the rye inside though, Susan & her parents are there looking shocked. Kramer (Michael Richards) & Jerry would have seen Susan walking into the apartment but this didn't happen.
George (Jason Alexander) says the Snitzer marble rye is too large to be able to be hidden under a coat, yet Frank (Jerry Stiller) was somehow able to take the rye back and not get caught.