I don't know if this has been documented before (like back in the "first run" years), but watching the Season Six DVDs, Episode 22, "The Diplomat Club" Jerry had a gig in Ithaca, NY. A scene setting shot was of the marquee purporting to be the "Ithica Civic Auditorium." Note the spelling of Ithaca. Later there was a shot purportedly of the airport terminal, and it was spelled correctly. Got a chuckle out of it.
You'd think various New Yorkers like Larry David, Jerry Seinfeld, and others would have known how to spell Ithaca, although they probably didn't control the scenery department or photography thereof.