Theory:Doctor Who television discontinuity and plot holes/The Invasion


 * Why does Vaughn continue to delegate tasks to Packer, who is obviously incompetent?
 * He can't risk him leaving or becoming antagonized with him as he could tell the authorities of the invasion, which he obviously knows about. Alternatively, Packer is the brother of Tobias, so he's keeping him in work because of the only being the Vaughn boys fear - Old Mrs Vaughn.


 * What happens to all the Cybermen that come out of the sewers? The Doctor and UNIT only seem to stop the Cybermen deliver their bomb and the Cybermen who have invaded are unaccounted for.
 * Attack of the Cybermen would later reveal some returned to the sewers. In episode dialogue reveals that UNIT plans to take care of the remaining after dealing with the Megatron Bomb and the Cyber-Spaceship.
 * The Cybermen from Attack are time travellers from Telos, so it seems unlikely they are connected to the Cybermen seen here. They were simply making use of their old hiding place and possibly the base left behind after this invasion.


 * In addition to the above, what do the Cybermen actually do after they have invaded? They are not really seen after the episode 6 cliffhanger, and characters seem to be able to move about without meeting them. Also, what is the point of seizing control of London in this way when the whole human population is under Cyber-hypnotic control at this point and the main invasion force is en route already?


 * Zoe and Isobel wait to be captured in episode 2.


 * In episode 4, the Doctor and his companions claim to have seen a ship on the moon - when they didn't.
 * In the DVD's animated episode 1 a ship was added to cover this up (you never see the moon in the original though).


 * How can human weapons harm cyberships?
 * The missles may have been modified by UNIT or Torchwood.
 * Why shouldn't they work? A bow and arrow can still kill can't it? Why can't what is as ancient (to the Cybermen) as a bow and arrow still fulfil its purpose?
 * Since the Cybermen expected that the entire armed forces of Earth would be conveniently paralysed during their Invasion, and since their current base world is low on resources (hence the invasion, as emotionless logic dictates they would not invade out of mere greed), they have probably not put a lot of effort into constructing such luxuries as armour and force fields.


 * Even if UNIT dating is taken from The Web of Fear being 40 years after The Abominable Snowmen (1935) and this 4 years later, that still leaves this in 1979 - 7 years before The Tenth Planet and well before any other Cyberman story (the rest being set well into the future) - so where do these cybermen come from?
 * Maybe some Cybermen survived the freighter impact in Earthshock and waited around 65 million years?


 * More seriously, Cybermen history is obviously ridiculously complicated. This wiki seems to accept the David Banks history in Doctor Who: Cybermen but there's no way to explain that entire theory on an entry on a page like this, and just saying, 'They're CyberFaction, not CyberMondasian' doesn't mean much on its own.


 * It's clear that some Cybermen left Mondas before its destruction or there'd be no more Cyberman stories. Silver Nemesis sees a large amount of space-faring Cybermen around only two years after The Tenth Planet. It's even possible, at a stretch, that these Cybermen are still in contact with the ones on Mondas or even came directly from there. (The comic strip The World Shapers identifies the Planet 14 they mention as Mondas although several other theories abound.)


 * Not to get into an argument UNIT dating, but it is explicitly stated in The Web of Fear that it is more than 40 years after The Abominable Snowmen. In Episode 2 Professor Travers states Why, that's over forty years ago. Not "forty years ago". Over forty. Therefore, Web of Fear must be set no earlier than 1976, and possibly years later. Sadly, it still doesn't gel with The Tenth Planet...


 * It's most likely that these Cybermen are time-travellers from the future, possibly wanting to secure Earth before Mondas arrives so that they can change history. As for how these Cybermen have time-travel while the more advanced models in Attack of the Cybermen have to steal their timeships, it's most likely that they're two different groups of Cybermen that drifted apart from each other, hence the different technology.


 * Adding time travel seems to me needlessly complicating things. Why can't these Cybermen simply be from Mondas? It's quite clear that the Tenth Planet invasion was a desperate last attempt to save Mondas. The Doctor's advice to resist the 1986 invasion is to do nothing, and, indeed, that's exactly how they're defeated. Mondas just expires on its own. That they would send a better equipped invasion force to subdue or eradicate life on Earth before Mondas arrive is perfectly feasible (the only issue looking at it from that perspective is the design of the Cybermen, but that can easily be handwaved by saying these are the advanced battle models while the cloth faced ones are the cyber civilians). It's essentially the same plan as the time travelling Cybermen from Attack of the Cybermen (weaken Earth so they can't resist Mondas absorbing the planet's life energy), only without the time travel.

Of course it's possible that after the Cybermen originally left Mondas that different groups ettled on different planets(eg. telos0 while some remained on Mondas. While all developed Cyber-technology, they did so at differetn rates and along different lines. The Cybermen that never left mondas developed the "cloth face" look and wouldn't arrive at earth until 1986, whereas other Cybermen who settled on another world reached Earth first.