Attack of the Cybermen - S22-E1
Revealing mistake: When Lytton stabs the Cybercontroller, some of the Cybercontroller's 'blood' gets splashed on the camera. (The 'blood' is green-dyed water spraying from the Cybercontroller's arm.).
Attack of the Cybermen - S22-E1
Visible crew/equipment: Just after the Cyber Leader orders that Flast be thrown out of the refrigerated room, one of the floor crew can be seen kneeling behind some crates. (01:20:50)
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