During the serving of the arrest warrant at the bank, the bodyguard drops his Glock pistol, which discharges due to the impact with the floor. This is impossible--all Glocks have a firing pin safety which prevents any movement of the firing pin without the trigger being pulled.
Early on, Hondo states that one touch of the pure stuff (fentanyl) will kill you. That's a common misconception. Even with fentanyl patches designed to allow absorption through skin, it takes hours.