I found one! A goof in Identity Crisis. When Brenner and Columbo first meet, and the other fellow finishes his speech, Brenner asks Columbo to step this way, near some chairs and a table. At that point, Brenner pulls something out of a briefcase that resembles a checkbook. Then the camera switches to a head-on, direct shot of Brenner and you can CLEARLY see he is holding paper with writing on it, no check book.