The Stakeout - S1-E1
Corrected entry: When, in the pilot episode, Jerry and Elaine are in the video shop, two women leave the shop. When they leave, you can see one of the women step down. That means, they are stepping off the set.
Corrected entry: After Jerry talks to Joel for the first time on the phone, George asks "who is this guy?" I'm sure that if George and Jerry had grown up together and have been close friends for so long, he would have, at some point in time, heard about him, or even met him. Especially if he keeps calling Jerry and trying to create a friendship.
Correction: Jerry is a stand-up comedian, and has met lots of people on the road at various comedy clubs, many of whom would have had no reason to have ever met George, so this mistake is not valid, as it is a guess, not fact.
Met no, but the mistake references the fact that George never -heard- of him before. If he's been 'stalking' Jerry with calls forever to the point that Jerry is even afraid of answering the phone, it's practically impossible that George never heard of him. An annoying person like this is exactly the sort of thing you'd expect them to talk about in their endless chatters about nothing.
Correction: It is possible that there was a step leading to the door of the video store.