Plot hole: John's plan to help Laura escape would not have worked, because he would not have been able to plan ahead like he does in the movie. He would have to know where Laura would be transported, and when, and if she would be transported there. He would not have known any of that as the information is kept secret from prisoners, and the public.
Suggested correction: Watch closer. He had a reasonable expectation of where they would take her because she was hospitalized in her earlier suicide attempt.
John would not have had an expectation of where they would since prisons keep inmates' medical updates, and whether they've been hospitalized a closely guarded secret.