Deliberate mistake: As Dale is taking photos of Bobby's ventriloquist doll you can see he is taking the photo from the upper right of where Bobby is standing in his house. However the angle of which he takes the photo from would be impossible as it's to the left of their screen doors and there is no window or see-through material from that angle.
King of the Hill (1997)
1 deliberate mistake in Now Who's the Dummy?
Starring: Brittany Murphy, Pamela Adlon, Mike Judge, Kathy Najimy, Johnny Hardwick
Bystand Me - S10-E2
Continuity mistake: While Hank, Peggy, and Bobby are asking for help picking up the papers with the dangerous ammonia and bleach recipe, a person in back of the group they are talking to that was originally wearing a dark red hat, red shirt, and blond hair switches to a pink, light blue shirt, and brown hair. A window also suddenly appears behind this individual, where there wasn't one before. (00:17:49 - 00:18:11)
Hank: Calm down, Boomhauer! I can't understand a word you're saying.
More trivia for King of the Hill
The Man Who Shot Kane Skretteberg - S2-E7
Question: When we first meet Kane Skretteberg, what is the song he and his band are playing in the garage? It is right before they start singing Funcenter over and over.
Answer: If you are talking about the "Thou shalt not do this, thou shalt not do that" song, I'm not sure if a song like that actually exists. Green Day, the guest voices on the episode, might have just been improvising to keep their appearance from being too obvious.