Question: Carrie asked Doug about what happened with his boss that day, which meant he could not have found out a problem with his boss from anyone else but Arthur. But then when Arthur comes in, she says "I heard you and Doug had a little adventure today", which meant it couldn't be Arthur, but then, who did she find out from?
The King of Queens (1998)
1 question in season 1
Starring: Kevin James, Jerry Stiller, Leah Remini, Victor Williams
Genres: Comedy
Two Thirty - S4-E24
Plot hole: In this episode Arthur scams Deacon and several other parents for phony piano lessons because he doesn't actually know how to play the piano. However, earlier in the series (Art House episode, S1 - E24) we learn that Arthur can play the piano when he temporarily moves out and after his house warming party Doug says to Carrie, "Who knew Arthur could play the piano like that?"
Carrie Heffernan: Ok, Maybe you're a little...big.
Arthur Spooner: Why is this even a discussion? The man's gargantuan.
Trivia: In many episodes when Doug is hurt, startled, angry etc., he will yell "Yuspa." Cathy Yuspa is one of the two writers on the show.
Answer: If she thought that Doug wasn't being totally honest about what happened, she may have gone and talked to Arthur - pretending that Doug had told her everything already - to see if he would reveal something.