Plot hole: During the scene where John (Russell) decides he needs to break into the medical van, he watches an infamous YouTube video about using a tennis ball to open "car door locks." Unfortunately for John, the YouTube video was faked, and in reality was proven to be fake on the TV show MythBusters. (00:55:40 - 00:56:30)
Plot hole: Modern diabetes management will tell a patient immediately if their glucose levels are out of the ordinary. Results are not monitored and delivered to a county jail by an outside lab. If a diabetic is sick enough, they would have obvious physical indications. The entire escape plan hinges upon these fallacies.
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.