Invasion of the Dinosaurs - S11-E2
Other mistake: The Tyrannosaurus rex which appears in this story does not actually roar; instead it says the word 'roar' several times. There may be little scientific evidence as to what sound a T. Rex made, but it is unlikely that any of them spoke fluent English.
Other mistake: After Linx plants his flag in the ground claiming Earth, Irongron and Bloodaxe look offscreen for no reason, as though the shot is finished.
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