Funny scene in "Ashes to Ashes" when Rita tells Prince that there is someone waiting in the display room. Prince opens the door and all you see behind an open coffin is cigar smoke. Once the two meet, Prince's first comment to Columbo: "I think you know the way out."

In MURDER UNDER GLASS, the first thing Sherea Danese does after meeting him is brush away the smoke, in more of a horrified way than an angry way.
I know nothing about her when it comes to smoking (cigars or anything else), so I wonder whether there was any "Life Imitating Art" situation afterwards when it came to her and the cigar smoking.

Nelson Brenner was also surprised Columbo didn't use a cutter; so was Calvert in A Trace of Murder. He says "You gnaw on it like a beaver." Funny quote.

In "Friend In Deed" he asks the sales assistant (Arlene Martell) at the jewellery shop whether it is OK to smoke inside the premises.

I'd forgotten that one.

Nearly my favorite is his second scene with Milo Janus. The idea of Milo giving a health and fitness lecture to the detective investigating his murder is pretty entertaining. Obviously he just couldn't help it, but either way it's entertaining.

One of the best subtle scenes involving his cigar for me was in Forgotten Lady. The impatient butler has his flip-top silver dish, holding it out under Columbo's hand thinking that ashes are going to drop on the carpet. When Columbo notices this overt behavior, he just slowly looks down at his ciger in his hand, turns the ash-end toward him, just to verify that in fact there's NO ashes to flick in the tray, but nevertheless gratuitously gives the cigar a slight tap into the dish where absolutely NOTHING comes off the cigar. LOL