Plot hole: Hock sneaks a gun into the prisoner interrogation area because he is told that guns are not allowed there. If the prison was so strict about keeping guns out of that area then they would surely have metal detectors to prevent such a thing from happening. (00:15:25)
Suggested correction: Not a plot hole at all. Most of the people who are allowed in those areas will be government employees, who will be deemed trusted enough to follow the rules.