I find one massive plot hole, They send the boy to the future so that the observers will never exist, yet without September Peter Bishop would have never came to this universe, making the end of the series impossible. Without September Walternate would have seen that his cure was successful, and Walter in this universe would never have went over to save Peter. Even if Walter had gone over to get him out of grief September still would not have been there to save Peter from drowning, therefore Peter and Olivia never meat, the never have a kid and they never have this happy life.