When Kramer is confronted by Cedric and Bob after burning the Puerto Rican flag, Cedric's dialogue is more muffled-sounding compared to Bob and Kramer's.
A sparkler wouldn't cause a flag to burst into open flame, it would merely smoulder.
After Elaine gets out of the car, there's some stock footage of New York City traffic. The lettering on the taxis are reversed, indicating that the film has been flipped from left to right.