Other mistake: The Cyber Leader is supposed to follow the Master's footsteps exactly in order to get across the chessboard. He doesn't. This cannot be classed as a character mistake because the Cyber Leader knew what was involved. I believe this mistake was caused by the actor not being able to see the chessboard through his helmet.
Revealing mistake: When a Cyberman's arm is sliced off by the Robot's shuriken, you can see his real arm bulging out at the right side of his body. (01:00:25)
Continuity mistake: After the Raston Warrior Robot has killed all the Cybermen, watch the dead Cyberman in the back right of the picture. His arm position changes as the robot teleports away.
Plot hole: In "The Five Doctors", Susan tells Turlough that she can pilot the TARDIS to some extent. During series 1 and 2, it was clear that she couldn't pilot it at all. She couldn't have been taught between episodes as the Doctor had little idea himself at the time.
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