I first noticed this only a few years ago and now I get a chuckle out of what appears to be two guys getting a chuckle out of watching them film a "Columbo" episode, in this case "Identity Crisis". Check out the two guys in the window over Peter Falk's right shoulder. If you watch the episode, you can see how the two guys watch the entire scene with Columbo and Sgt. Kramer. It cracks me up every time I watch it now.