I get the feeling where he breaks his shoelace in Exercise might have been unscripted.

in "Murder by the Book", the script has Falk saying the secret to a good omelet is "no milk, just eggs." In the actual show, he says "no eggs, just milk". It's either a flubbed line, or an ad-lib, I don't know which.

I heard Peter talk about this one......In "Any Old Port" Peter was on the phone waiting on hold and started whistling This Old Man, that one was an ad lib, it stuck and sort of became an unofficial theme.