Revealing mistake: When Noah bangs his green arm down, in a close-up you can tell that the arm has green bubble wrap around it. (00:02:30)
Revealing mistake: When Vira emerges from the hibernation chamber, the Styrofoam that forms the pallet squeaks.
Revealing mistake: As the cast move through the transom of the space station, observe the starscape through the lower windows. At certain points you can see a thin strip of light where the black curtain used for the stellar backdrop meets the studio floor.
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