(Around 19 minutes) When the Ghost asks who the Doctor & Nardole are he is pointing at them with his right arm but in the next shot his arm is by his side.
When "Dr. Mysterio" first enters, he is shot at, and when the gun runs dry, it simply makes a click click sound, but this is incorrect. The pistol is a striker fired semi-automatic, when the last round has fired, the slide should be open and locked back, yet this one is closed. Also, even were the slide hold open to fail, there is no hammer to repeatedly "click;" the striker is spring loaded and held back by the sear, when the trigger is pulled, the sear drops and allows the striker (firing pin) to move forward against the primer under spring pressure, this would indeed make a "click" sound, but it does not reset until after the round is fired and the slide cycles (or one manually cycles the slide). So even if the slide hold opened failed, there would be only a single click, not multiple.