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


 * If this is during the middle of Dalek history, why did the Daleks on Skaro not use disks on their backs to exit their city?
 * It's not the middle of Dalek history. The Doctor was clearly mistaken when he said this. The disks appear to only be needed by this group of Daleks for this particular mission of theirs. And indeed, in episode 2 the Doctor explains exactly this to Chesterton.


 * The Slyther changes appearance between episodes 4 and 5 as the production team were not happy with its appearance.
 * Many species change their appearance easily.


 * When Ian and Larry meet Ashton the Slyther cries for the first time, over Chesterton's line. He does not pause nor otherwise express surprise or horror.
 * Animal noises at night are not necessarily unusual or alarming - until they get too close!


 * Two studio technicians are visible outside the Dalek saucer in episode 2.
 * They could be prisoners of the Daleks.


 * Jenny and Barbara have to hold their own neck restraints in place.
 * It is not a problem, it looks more like they are trying to pull them off or give themselves room to breath.
 * It's probably too heavy for them.


 * When the Daleks are in Trafalgar Square, cars can be seen to drive past.
 * Pushing it somewhat, but these could (just) be Robomen on vehicle-based patrol, or the resistance cells making use of discarded vehicles, as Barbara and Jenny later do.


 * Pleasure cruisers can still be seen on the Thames.
 * Like the theory above, this could be a patrol boat used by the Robomen which resembles a Pleasure cruiser.
 * Similarly, it may have been hijacked by the robomen and actually was one prior to the invasion.


 * Boom mike shadows are visible in episodes 3 and 6.
 * Could be trees or lampposts.


 * Why do the Daleks need intelligence tests to determine who can become Robomen when they are mindless zombies?
 * Allegedly, the more intelligent the human, the longer the Roboman will function.
 * Also, they may be required to perform mental calculations.
 * Or possibly this test is to remove the clever ones?


 * Just what is the Dalek doing in the river in episode 1?
 * The Daleks are in Dalekanium shells, and therefore cannot distinguish between air and water. The Daleks are probing the Thames for some reason; possibly a scientific expedition- are the fish a threat to the invasion?! or it is searching for the suicidal roboman's body.
 * Quite probably some of London's bridges will have been demolished in the anarchy and invasion, and the Dalek is too impatient to bother crossing the nearest one in order to join the patrol. At any rate, it makes for a nice, early gesture of power and adaptability to the critics of Dalek mobility.


 * The Black Dalek, before addressing the humans, clears its throat.
 * Who says the Kaled mutants don't have throats of some sort at this point in their development?


 * Why did the Daleks locate their mine in Bedfordshire rather than somewhere where the Earth's crust is thin?
 * How do the Daleks know where the Earth's crust is thin?
 * They probably choose a small area that would have little resistance; if they drilled in New York there may have been more resistance.


 * During the first episode, while the Doctor and his companions are exploring their materialization place next to the Thames, the TARDIS windows are clearly propped open (inwards). Examples are at 2 minutes 12 seconds through 2 minutes 16 seconds, and elsewhere during the same scene. Were they just traveling through space and time with the windows open?
 * The TARDIS exterior faithfully matches a genuine police box - the windows are seen to be open in other early stories such as The Web Planet. The TARDIS shell is clearly not as simple as a wooden exterior, which would imply that it cannot be airtight. The Doctor later describes to Donna that there is a shield protecting the interior. It has been stated that the interior is in another dimension to the exterior (such as The Robots of Death).


 * After taking Barbara and Jenny prisoner, the Dalek that takes them across the control room of the Dalek saucer can be seen bumping into the Black Dalek.
 * Even murderous killing machines can be clumsy sometimes.


 * In episode 4 when they meet Ashton, the interior is seen to have a window - something not seen on the exterior.
 * Not on the side we see.


 * In the prison where the Doctor is held on the ship, another set behind the railings can clearly be seen, complete with Daleks moving about.
 * It's part of the same ship, which of course contains Daleks.


 * At one stage in episode 2, a Dalek can be heard saying "All" - the start of the next line (This is because it was pre-recorded, and couldn't stop the recording in time).
 * The Dalek was saying something and was interrupted.


 * The paint design of the Black Dalek changes after episode 2.
 * The first one was the commander of just the flying saucer, the second one was in command of EVERY Dalek on Earth


 * The use of cardboard Daleks outside their ship.


 * This isn't really a continuity error. They're meant to represent Daleks, just as the high-quality models (and later CGI) are; high-quality Dalek models (and CGI Daleks) are not Daleks either.


 * During episode 5, when the Black Dalek moves through the door, a production assistant is clearly visible to the Dalek's right.
 * A Human Slave.


 * The 'It is forbidden to dump bodies in the river' sign is visible during the miners' revolt in episode 6.
 * There's no reason to assume they don't have the sign posted in multiple places.


 * If the Daleks are drilling to the Earth's crust, wouldn't that blow it up?
 * They have other methods than the ones used in Inferno. The Doctor mentions that they are manipulating living energy to avoid explosions.


 * Judging by what Susan says to Tom about 'Grandfather getting old now' and her needing to look after him, it seems that she doesn't know about regeneration.
 * Perhaps it would be hard for her to explain regeneration to Tom or perhaps she knows when he is going to regenerate and she wants to be with him. Also, she does not know for sure that he will regenerate into a younger body.
 * All she says is that he's getting old now, which does make things physically difficult for him at times. This makes no implications whatsoever other than that Susan cares about the Doctor's well being.
 * There is no overly convincing way to square this point with later continuity, but it may be that Susan believes the Doctor is in his final incarnation, or at least close to the end of his cycle. The Morbius mind-bending sequence implies many previous regenerations, and Susan may be unaware that the 12-regeneration limit does not necessarily apply to the Doctor (though for that, and other controversies, it is perhaps better to pretend that "Mawdryn Undead" never existed...).
 * A Time Lord can also choose not to regenerate, so for all we know the Doctor may have expressed the intention of making his life with Susan his swansong (we know he has had a dark past...), before Ian and Barbara helped him get in touch with his heroic side and thus gave him new purpose.
 * Or perhaps she genuinely doesn't know. The series, at any rate, offers no canonical explanation of who or what Susan actually is.


 * When Tyler and the Doctor are hiding behind the walls, the last Dalek to pass by has the eyestalk pointed in the Doctor's direction, yet he does not notice Tyler or the Doctor.
 * There have been many Anti-Dalek attacks during the occupation; it is likely that many Daleks have been damaged (this one has poor sight from damage to the eyestalk).


 * When Barbara and Jenny are taken to the Dalek command centre, they devise a plan against the Daleks. They talk in full voice, while the Dalek guard is directly behind them. Its only response is a command to 'stop talking'.
 * As the Dalek that comes out of the river in episode 2 says they have heard in the time that they have controlled the earth many similar plots to over throw them that have all failed so they have probably got to a point where they don't pay any attention to them any more since they know that they are going to fail.
 * Possibly more of a production error, or an expediency to compensate for poor studio microphones. The viewers are supposed to suspend disbelief and assume they are whispering almost inaudibly (even though they clearly aren't).


 * In Episode 5, the Dalek supervising the mine clearance has broken speech-synch lights, and instead chooses to wiggle its eyestalk about while talking.
 * As stated above many Daleks are likely damaged after resistance attacks, and the Dalek may wave its eyestalk the same way a human slave-driver would wave their hand as another way of saying "hurry up!".


 * The Daleks have invaded Earth for their plan because they say that no other planet has a magnetic core, but magnetic cores are common and all the planets in Earth's Solar System have one.
 * Of the terrestrial planets, Earth has the largest magnetic core, and the largest magnetic field.


 * See The Stolen Earth for an alternate explanation.
 * Which would suggest that the Skaro system is close to our solar system, or at least the closest that contains an earth-like planet. One might ask why they didn't remove the core from their own planet? On the other hand, the core may be only one reason for choosing earth, and not necessarily the first one. If the events of The Daleks were in fact in the past relative to Earth, as the Doctor states, the Dalek survivors passed on memories of the travellers from Earth. So perhaps the Daleks regard Earth as a threat to their empire.
 * Which would suggest that the Skaro system is close to our solar system, or at least the closest that contains an earth-like planet. One might ask why they didn't remove the core from their own planet? On the other hand, the core may be only one reason for choosing earth, and not necessarily the first one. If the events of The Daleks were in fact in the past relative to Earth, as the Doctor states, the Dalek survivors passed on memories of the travellers from Earth. So perhaps the Daleks regard Earth as a threat to their empire.


 * In The Runaway Bride, the tenth Doctor learns that a Racnoss ship had been hidden at the centre of Earth at the time the planet formed. This could have resulted in Earth's magnetic core exhibiting truly unique properties.