The three $100,000 wins. The last one, also the only win of Season 2, had five Drop Zones in play.
There was one episode where a man named Pat started out as the challenger. He never did anything else and survived to the penultimate round, when the other guy, after answering himself for a few questions, decided to challenge him. Mark said, "Ladies and gentlemen, Pat is going to answer a question now." The audience then applauded and cheered at this. But then, Pat proceeded to get the question right and challenge his opponent on the next question. The opponent got the question wrong, all of his money went to Pat, and time went out, meaning that Pat won by only answering one question. Then, he won the $10,000. He didn't go for the $100,000, but it should be noted that in Season 2, if you decide not to go for it, the Drop Zone will never stay shut to prevent a Tear Jerker. If one looks closely at when Pat tried to see what would have happened, he would have won the $100,000 by answering only 11 questions in the whole game.