During the scene in which Mickey (Danny Woodburn) & Jerry (Jerry Seinfeld) almost have a fight, we hear Mickey say, "I knew I was crazy to try this kind of thing...". His lips however, don't match the word that come out of his mouth.
When Elaine (Julia Louis-Dreyfus) is asked how her date went by Jerry (Jerry Seinfeld), one hand is holding her purse, while the other is in her lap. There's a change in the camera angle and suddenly both her hands are folded in her lap.
While Kramer and Mickey are playing "Rock, Paper, Scissors" Mickey says nothing beats rock. That is incorrect. Paper covers rock as Kramer said.