I am not sure there is a confusing part. I think that student smight need some guidance on the emergence of Brian's "tough hope" before he is rescued. There is a certain hardening of Brian's character that might require further detail and explication. It is not something that can be immediately felt and grasped. It takes some time to sense the resolve that is within Brian that suggests he will be rescued or will die in the wild. This involves a level of commitment that seems, on one level, surprising. Yet, on another level, it makes sense that this is a point in Brian's exploration of self. Paulsen writes it in such a way that it makes sense, but is a point in the novel where one has to be mindful of it. This might require another reading, as students sometimes miss the change in Brian's character.
When it comes to issues such as confusing themes, plots, or analysis in any novel, it always depends on the reader. For most readers who have read the novel Hatchet, I would not expect people to be confused too much in such a book. The book is purely based off of surviving in the woods, maximizing your few resources, and learning how to work in an unfamiliar and uncomfortable environment. This book, in my opinion, was fairly straight forward and very enticing to read. It kept me hooked because of the way Brian was able to uniquely create techniques that helped him survive. The way Gary Paulsen, the author, also wrote it and described every detail throughout the novel, also made it quite easy to understand. The simplicity and straight forwardness of the book is what makes it very attractive towards Middle School and High School English teachers to incorporate it into their teachings.
Perhaps it would be easier to find a confusing part if you specify what you are asking. What is the motivation behind wanting to find a confusing part? This would help provide a better answer.