I'm not always good at spotting these things by a long shot, but to me the whole final scene with Nora Chandler makes it seem like Anne Baxter was allowed to do it exactly the way she wanted to, and I think that worked out very well.

Agreed, Grant! There doesn't appear to be much scripting in this last scene, but, as you mentioned, perhaps she had a bit more freedom than most others have had in the final scenes. I should not, however, that I have read somewhere (the exact location escapes me currently) but that 'Nora' had memory problems and that could, perhaps, be the reason for her unshaken scenes, but this is all conjecture on my part. Any thoughts, Grant?

When Robert Culp is setting up the murder in the episode about the motivational film (I am loosing my memory!) it seems that a lot of what he says, as he imitates an angry/sad boyfriend/street guy, was improvised. That is the scene where he calls up the victim's wife to get her to a Magnolia and Vine. Just an opinion.

in Publish or Perish..the scene where Columbo is eating chili in the fancy restaurant questioning Mariette Hartley and Jacques Aubuchon...
when he goes to leave...he starts to get up and sits back down...stating.."Im having a hard time getting up"...both actors seem to snicker a bit....funny subtle moment

The scene at the end of "Fade into Murder" when Falk and Shatner are fooling around with the video recorder strikes me as an improvisation.

Yes, that makes sense.

I don't know about improvised, but one moment that strikes me as funny is when he's in that hospital waiting room with Milo Janus and he grabs that magazine. It's funny because, what are the odds of someone that infuriated managing to read even one word of the thing? But it also makes sense, because that's just "what you do" in a waiting room. So I wonder whether that was Peter's idea or not.