I don't know if I posted in this thread before, but 31 springs to mind. It strikes me as the book with one or two of the biggest plot holes. Yes I'm aware that Yeerks die if they don't feed every three days, and this was going to be a four day trip. However, it's established that Tom's Yeerk was reasonably important and there were small portable Kandrona machines that important people use. Could he not pull any strings to borrow one just this once? Did Yeerks really never have any contingency plans for travelers? If all else failed, could he not have some people follow him and switch Yeerks? I don't know how Yeerks feel about others borrowing their hosts, but it's better than starving to death.
Also I don't think Jake ever thought that this was a great time to plan a rescue. It should be easy. Starve the Yeerk out and have Tom fake a suicide. The Yeerks would believe that Tom committed suicide, and would have no reason to believe the bandits were involved in the Yeerk's death? Why would they if they never made plans for the even of a four + day trip away from the main pool complex?