Audio problem: Before the TARDIS materialises in the haunted house, you can hear The Daleks' time machine sound effect for no apparent reason.
The Dalek Invasion of Earth - S2-E2
Audio problem: In episode 2 you can hear the Black Dalek clear his throat before speaking.
The Dalek Invasion of Earth - S2-E2
Audio problem: When the Doctor says that what they're seeing now is the middle period of Dalek history, you can hear a metallic thing being dropped off screen.
The Dalek Invasion of Earth - S2-E2
Audio problem: When the Dalek says to give the Doctor and Ian the test, it cuts to the prison cell where you can hear a Dalek voice that gets cut off.
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