Factual error: During the entire series, the view of Jerry's door from the hallway is of a flat wall with the door in line, yet from inside the apartment, not only does the kitchen angle into the hallway, but Jerry's fridge is recessed into the wall. The wall behind it should be blocking the hallway completely.

Continuity: Throughout the whole show, George Costanza is showed as being left-handed (eg. at the beginning of the episode titled "The Shoes", Jerry and George are writing "The Butler" script, and George can clearly be seen writing with his left hand). However, the actor himself is not, and you can spot some episodes (mostly in the first seasons) but a few in the last seasons as well, with him using his right hand for writing or eating, while in most of the show he's using his left-hand for everything.