Did Kramer actually fall down on every single episode or just it just seem that way?
It just seemed that way. Of course thats an opinion based only on memory.
No, you’re thinking of Matthew on Newsradio. 
I don’t think he fell down in the pilot…
no, but in the finale, he fell down on the pilot…
Actually fall down every episode? Nope.
He didn’t even make his trademark entrace to Jerry’s apartment every episode.
Was he even in every episode? I know that there’s a couple Elaine isn’t in because she’s on holiday somewhere.