Continuity mistake: The door to the slaughterhouse (which Luanne blocks with the barrel) changes configurations between shots. When Trip is trying to get in, the exterior is blue with a doorknob. After Peggy busts in, it is white with a pushbar across the middle. The interior is white with a pushbar in all shots.
King of the Hill (1997)
1 continuity mistake in Pigmalion - chronological order
Starring: Brittany Murphy, Pamela Adlon, Mike Judge, Kathy Najimy, Johnny Hardwick
It's Not Easy Being Green - S5-E16
Factual error: Boomhauer's car, Ms. Sally, has a Texas flag license plate on it. These plates were not issued until 1992, but Ms. Sally was driven into the quarry in the late 70's or early 80's.
Peggy: It was like a knife in his heart when she stuck that fork in his back.
More trivia for King of the Hill
To Sirloin with Love - S13-E20
Question: What is Boomhower's occupation?
Answer: Jeffrey Boomhauer is a Texas Ranger as can be seen in the final episode at the end when he sets his wallet down, it flips open revealing a Texas Ranger badge.