Theory:Doctor Who television discontinuity and plot holes/The Greatest Show in the Galaxy


 * When The Doctor and Mags escape from the cage, why does a simple pat on the abdomen and on the back of the head disable the robots? That wouldn't even knock out a human.
 * Perhaps The Doctor recognized this model of robot and knew that a tap on the abdomen and on the back of the head will reset them, a sort of "ctrl-alt-del".
 * Or perhaps, being clowns, they are programmed to perform unlikely pratfalls after any violence whatsoever (though that would, admittedly, be a glaring oversight in repurposing them as ruthless killers).
 * At another point in the story, we learn that the Bus Conductor robot can be deactivated by hitting a shutdown button on the top of its head. Presumably, the Doctor simply knows where these types of robots have their shutdown buttons and is activating them.


 * Ace asks the Chief Clown if he is also a robot when she first meets him, but she is never shown being made aware that the other clowns in the circus are robots to begin with.