When the foreign girl sits on Kramer's (as Santa) lap, her mother places her hand on the girl's left shoulder. In the next shot it is on her right shoulder.
We see Elaine (Julia Louis-Dreyfus) cheering for Jerry (Jerry Seinfeld) when he is racing Duncan (Don McManus) at the end of the episode. When we see a closeup of her moment later, the people surrounding her are different to those shown just previously.
Elaine (Julia Louis-Dreyfus) is getting told about the race from Jerry (Jerry Seinfeld), she puts her glasses at the front of the coffee table, but in the next show they can be seen on the other side of the table.
The idea that Duncan and Jerry should race again to prove whether or not Jerry cheated makes no sense. Jerry (who was willing to lie to keep the lie going) could have simply said that he was injured, had a surgery, or something along those lines between high school and the present.
Kramer says he's working as Santa Claus at Coleman's, yet the establishing shot of the department store is Conway's at Herald Square.