My favorite edit was one on Hallmark about five years ago; it was in the "Yes, We Have No Havanas" episode.
After Blanche told Sophia that Sophia could have Fidel and Sophia (amusingly) said, "okay, good night," whomever edited the episode inserted music that signals a commercial break (as the camera lingers on Blanche's face), the screen faded to black, and the dialogue picked up in the middle of the next scene. Hard to describe, but it was absolutely ridiculous.
It was also ridiculous, and hilarious, when Dorothy told Barbara Thorndyke to "go to hell," and the audience's response was superimposed over the dialogue. (Quite loudly, too.)