Hank's Unmentionable Problem - S1-E6
Factual error: Hank is extremely constipated, but has a colonoscopy. He would not have been able to have a colonoscopy while extremely constipated, having not had a bowel movement in many days.
King of the Hill (1997)
1 factual error in season 1
Starring: Brittany Murphy, Pamela Adlon, Mike Judge, Kathy Najimy, Johnny Hardwick
Returning Japanese (1) - S6-E21
Plot hole: In this episode, Hank meets his paternal half brother. They look alike. However, we saw in an earlier episode that Hank's facial structure takes after his mother, not his father. Since they are paternal half brothers, then the Japanese brother cannot look like Hank since he has a different mother.
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.