Revealing mistake: The Grove is one of the most obvious indoor sets masquerading as a lush outdoor environment. The sound the actors' feet make on the floor is especially unforgivable.
Revealing mistake: In episode 1, watch out for the wires pulling K-9 along the beach. (Unlike a real dog, K-9 didn't take well to the soft sandy surface and sank into the sand. Pulling K-9 along on wires provided an illusion of movement when the motor inside wasn't up to the job).
Revealing mistake: When the Keeper is on the TARDIS, he asks to borrow the screen. But on the upper left corner, you can see it over where it's meant to be.
Answer: In 'The Five Doctors', three separate Cyberleaders are definitely used. So it's likely that Cyberleaders are like unit commanders, of which a fair-sized army might have several.
Daria Sigma