I like the way you put that, John. Not only did Ken Franklin have to sell some paintings to pay his lawyers, he also had to sell his Mercedes-Benz, license plate and all, to Elliot Markham. Of course, Elliot went on to commit murder himself in "Blueprint For Murder".
You don't suppose all these paintings and the car are possessed by evil entities who inspire those near them to commit murder?!
Great observation, Kevin! But yes, this is one of several such callbacks across episodes, that are featured in the Columbo Scrapbook article on this site, "Columbo Flashbacks" -- it is number 5 in the collection:
And long after the Scrapbook article was done, a post on tis Forum pointed out that a painting by Sam Franklin in "Suitable for Framing" makes an appearance on the wall of the hospital waiting room in "Exercise in Fatality. You can use the Forum's search feature to look for "Sam Franklin Painting" for details, although unfortunately the links for the images are expired.