At the end, it is clear that the murderers planted the murder weapon in Mrs. Columbo's car and it was at the police ballistics lab. <br /><br />But where did the gun under the hood, used in the demonstration, come from? Wouldn't the murderers have cleared out the stuff under the hood? They had a whole week? Or did Columbo's cops replicate the camera/gun under the hood used in the demonstration? How did they do that without breaking and entering the car? Perhaps this is why the murders seemed surprised at the end. But how could Columbo have replicated their camera/gun device and gotten it calibrated to their key fob? Columbo must have gotten the gun back from ballistics and had it re-planted under the hood of the car, and been very lucky that the rest of the device with camera was still there and transmitting.<br /><br />This was a 10/10 show until this glaring plot error at the end.