Theory:Doctor Who television discontinuity and plot holes/Resolution


 * Why does no one seem to remember the Dalek invasions of 2007 and 2009? (Doomsday (TV story), The Stolen Earth (TV story))
 * Bluntly, just lazy looking after of previous continuity.


 * In series 5, the Doctor was surprised Amy couldn't remember the 2009 Dalek invasion. It was revealed later on that the cracks in time had erased the RTD-era invasions (and possibly some classic ones). This is why it wasn't common knowledge in the Moffat-era that aliens existed and why Graham didn't believe they did in The Woman Who Fell to Earth.


 * Those events were not permantenly removed from the timeline. What did captain Brooke do then? How did Davros have footage of that event? And why is Rory suddenly back but these events aren’t? Cracks didn’t wipe it for good. It’s an assumption that made the writers wrongly not get pulled up for their bad connections.


 * Not really. Big Bang 2 completely reset the universe so it makes sense that some things were rewritten. Plus, it's all 'timey wimey' anyway; some points are fixed and others aren't. But, to answer each of your attempted counters: 1) Brooke is unknown, but we don't need to know. Afterall, the episode occurred in 2019, so it does not contradict what happened in the 2050s. 2) Davros is a genius, so naturally he has technology capable of viewing messages/footage across all of time and space in all various realities/timelines 3) Rory was different as he'd travelled in time and was a single individual rather than an entire event; the Doctor has previously established time travel affords one a special kind of protection. Plus, the Doctor reset the universe so he had some power over exerting how the universe banged back in to being.


 * A dalek has no emotions except for hate and fear. How then can it laugh?
 * It has been established previously that Daleks should not have a concept of Beauty or mercy but Asylum of the Daleks, The Big Bang and The Witch's Familiar revealed flaws in that. Plus, perhaps the Twelfth Doctor's encounter with Davros meant he imprinted more than just the aforementioned onto the man and his creations.
 * This Dalek was created long before the Twelfth Doctor came into being.


 * They mean when 12 met child Davros. Which was before any Daleks were created, why is why mercy was inadvertently imprinte


 * If technology of the 9th century can disable a Dalek why is the Doctor so anxious about it being in the 21st?
 * The Daleks are still a threatening menace to defeat + it's implied it took the combined forces of three empires to defeat it (given were told at least three nations were involved in taking it down.) Further, the Doctor appears more concerned with the Dalek contacting off-world Daleks to launch an invasion more than the threat the sole Dalek can produce.
 * And yet she taunts the dalek with being unable to prevail back in the 9th century and manages to disable it simply by running up to it and strapping on bits of a microwave. (Whereas soldiers and a tank stood no chance against it!)
 * The Dalek was able to block the tank shell; note the soldiers never got as close as the Doctor and company got to take it down. Plus, it's made of earth metal found as a work mill on a farm; naturally, it's more vulnerable than actual Dalekanium.


 * Unit? Budget cuts? Really? Isn't Unit supposed to subject to the UN anyway?
 * This doesn't really contravene continuity. Where has it been established that UNIT is exempt from such financial constraints?
 * Unit wasn't subject to the UK or even the EU. It was a UN organization. Brexit shouldn't affect it.
 * Perhaps it does - we have to remember the EU and Brexit in our world is not the same as that as the Whoniverse. Thereby, the EU and UN may be more intimately connected so Britain's split from the EU also has ramifications on the UN and Britain's relationship as well.


 * If this is supposed to be one of the earliest Daleks to leave Skaro, why is it designed like a recent Dalek?
 * Because Chibnall shows no respect for canon. This is a good point. Also it should not be able to fly.
 * We have never seen a recon Dalek before so it's reasonable to assume it possesses a different design and capabilities. Further, the comment about Chibnall is not needed.
 * Any comment about Chibnall pushing discontinuity is needed


 * How can the dalek obtain all the technology it requires from a Sheffield junkyard?
 * It doesn't the Dalek is shown raiding a security archive that had access to alien tech.


 * When the doctor realizes what they discovered in the sewers, she says "there's been a Dalek buried on earth since the 9th century." Mitch then asks, "a what?" and Graham replies "an alien psychopath" describing what a Dalek is. But Graham hasn't met any Daleks yet. He shouldn't know what they are any more than Mitch does.


 * It's feasible that the Doctor merely told Graham about the Daleks, or that he had encountered them in some as of yet unseen adventure. Or maybe Graham actually remembers one of the several past invasions that the show is really inconsistent about.


 * If Graham remembered, Mitch should have. The only other explanation is your "it happened off-screen" hand wave, which isn't disprovable, but would also be highly inconsistent with previous introductions of companions to recurring villains.