Possible Spoiler!!!!
If I were the Mole what could I do to sabotage the challenges?
1. Although one person thought that picking odd items to sell would be molish, I think trying to sell ANYTHING would be difficult. Knowing that the women would most likely volenteer for the shopping portion of the challenge, (and the fact that the Mole is male) it would be suspicious if the Mole said they liked to shop. The language barrier is the problem here. Try to get a bargain if you can't speak the language. Also, try and sucker locals to buy something for more than its worth. (Al sold 2 pair of shoes for a total of $25) The Mole didn't have to try to hard in this game. It was a near impossible game to win.
In the second game, what could the Mole do to sabotage it? How about controlling the radio that tells the tracker where to find the other person. The Mole can control when the tracker takes off. He can appear to hit the call button and just talk out loud to make it seem that he is really talking to someone.
I still say its Bill. I'd like to be wrong because it would totally blow me away and make me watch all the episodes again.