Fans noticed that Ken Jennings showed the other side of the Final Jeopardy card by chance on Friday's show.
A game show like Jeopardy! superfan noticed that the most important part of the game show was shown quickly at the end of the game.
Host Ken, who is 48 years old, was saying goodbye and cheered for three-day winner Ben Chan, who won his third game and a total of $69,001.
Ken said that Ben would be "back raising the roof" on Monday's show.
During this, he made a hand move like "raising the roof" and accidentally showed the front of the clue card, which is usually only for his eyes.
The cue card had a table with different words and notes written in it. It also had a few lines.