Theory:Doctor Who television discontinuity and plot holes/Cold Blood


 * This story contains a several time paradoxes: If Rory was wiped from time, so he never existed, then who saved the Doctor? Rory was only absorbed by the crack because he died, but if he never existed then he would never have died, so how was he absorbed? If he never existed who convinced them to take Alaya's body down to the Silurians? Who saved Amy from Francessco? Who convinced Ambrose to trust the Doctor? Who helped the Doctor capture Alaya in the first place?


 * The events prior to Rory's absorption is re-written. Many of the other characters could have taken Rory's place. Events may have also been unwritten or rewritten. As for each question; 1) the Doctor may have simply destroyed the gun as he was about to do with his sonic screwdriver, b, no wait, 2) that's part of the cracks and their mysteries, 3 or c) if Rory wasn't alive she may not have died so they may have taken her down. 4) Amy wouldn't have been there in the first place, e) Amy? She can be pretty convincing, and f (for finally)) Ambrose or her dad could have easily taken his place.


 * It should also be noted that the events in the past being erased do not affect the situation of the present, especially within something displaced in its normal spacial-timey-wimey co-ordinates. Such an example would be Amy's engagement ring.


 * But usually, they do affect the present (and future). We often don't notice, because we're typically watching the adventures of the Doctor and his companions--who, as the Doctor explains in Flesh and Stone, can (generally) remember the original timeline. For everyone else, changes in the past really do change the present. This is why only Amy is waving at the end of Cold Blood--because (in Amy's timeline), Rory never existed.


 * The ring is intentional and not a continuity error. There was a scene specifically for Rory placing it there, that was even included in recap for part 2 (for no other apparent reason). Similar to the jacketed Doctor telling Amy to remember in Flesh and Stone (although I am less sure about that one).


 * Only the memories of people/events are erased, but they still all happened.


 * That's possible, but if that were true, then it wouldn't actually be possible to unwrite/rewrite history, and the Doctor said (in Flesh and Stone, for example) that it is possible.


 * It's all just part of mysteries of this show, we don't know if the writers had intended for us to do all of this deep thinking we're just supposed to go with it.


 * One rule of time travel is that if events of the past are changed, time-travellers are not physically changed at all and their present situation is not changed (like in Back to the Future II where the world changes around them or they fade etc.) but their mental self may be changed slightly, as witnessed in The Waters of Mars when the Doctor views Adelaide's profile changing from her death being on Mars to her death being on Earth.


 * There are many ways of dealing with time travel in fiction, and there's no evidence that time travel works the same way in Doctor Who as in Back to the Future II. In fact, there's pretty solid evidence that it _doesn't_. People's situations change all the time. It's only "fixed points in time" that can't be changed; everything else is "in flux", as the Doctor has explicitly explained multiple times.


 * First, time-travel paradoxes aren't discontinuities or plot holes if they're intentional. In the long history of the show, paradoxes are created on an almost weekly basis, and they're implicitly explained as well.


 * Every time an object or idea from the future is left in the past, that changes history, and creates an ontological paradox. The Empire State Building was designed by the Cult of Skaro--but they designed it based on the future Empire State Building from the original timeline. Some of Shakespeare's best lines were given to him by the Doctor and Martha, who knew them from his plays in the original timeline. And so on. The Curse of Fatal Death is all one big chain of ontological paradoxes (and yes, it's a parody, but it works as a parody because it works the same way as the real show). In every case, there is no cause for the object or idea to exist within the new timeline--because the cause is the original timeline. And the ring is at least as simple as all of these cases. In the new timeline, with Rory erased, there is no cause for the ring to be there--because the cause is in the original timeline.


 * But the show has a ready-made solution to ontological paradoxes, which they explain explicitly in Flesh and Stone. Time travellers can remember the original timeline. In some sense, it still exists, it's just that only time travellers have access to it.


 * For the specific example, "Rory was only absorbed by the crack because he died, but if he never existed then he would never have died, so how was he absorbed," if you take this seriously, it's just an argument against time travel ever being able to change the past. After the Doctor hid the Hand of Omega in 1963, the Hand of Omega existed in 1963, so he had no reason to go back and hide it in 1963, right? So, why did he do so? Well, because in the original timeline it didn't exist in 1963; after he hid it, that created a new timeline, where it always existed. But the Doctor doesn't live on that timeline, he lives on a big loopy timeline that crosses both the original and the new one. That's what time travel means. If Rory being erased is a discontinuity, pretty much the entire show is a discontinuity.


 * If this is all too complicated, here's the simple version: Wibbly-wobbly timey-timey. Time is not a simple straight line, your common sense is wrong, deal with it.


 * Maybe the TARDIS is resistant against time-changes?


 * There are a lot of good explanations here, but I always just thought it as being that Rory wasn't literally erased from time and space, only from the memories of all who knew him, that time was re-written in their minds.


 * How come the Doctor didn't get erased from time when he touched the crack?


 * It took some time for Rory to get erased. And presumably absorbing a "complicated time-space event" like the Doctor is a lot harder than absorbing Rory. And you could see and hear that the Doctor was struggling with something the entire time his hand was in the crack (unless Matt Smith was just doing a 2nd Doctor impression for no reason).


 * In Flesh and Stone the Doctor says to River that if they throw a big time event in to a crack then it should slow it down maybe the crack was trying to avoid absorbing his power. Also the Doctor is a Time Lord and so can probably reject things like this for a while.


 * In both The Eleventh Hour and Vampires in Venice, some beings are able to use the crack to travel between two points in time and space. The crack seems to undergo some kind of visible change in Cold Blood before consuming Rory. Further, Rory was consumed by some sort of energy coming out of the crack, not by falling into it. It may be that the crack has (at least) two different "phases", and is only dangerous in its "eating" phase.


 * Or it's just random. Remember that Prisoner Zero was able to go through a crack without being eaten, maybe the way the cracks work is just really finicky.


 * The Doctor tells the Silurians to wake up in 1000 years. However by that time, humans have evacuated the earth due to solar flares.


 * That could be intentional--let the Silurians have the planet, no conflict necessary (assuming the Silurians can survive the flares even though humans can't).


 * That would make the narration at least a little odd.


 * It's also more devious than what we've come to expect of the 11th Doctor (although for, say, the 7th, it would be perfectly in character).


 * Yeah, shouldn't the Doctor tell them to wake up sometime later than that, since when the humans eventually return to Earth only to find it in control of the Silurians, there would probably be a war.


 * If everyone in Cold Blood passed on the message that they would re-awaken in 1000 years, then the humans should have no conflict against the Silurians. Since the humans have found a way to escape the Earth in 1000 years time, they would probably carry on travelling the universe, instead of going back to Earth, so the Silurians have it.


 * In addition, perhaps the point of the Doctor's timing was so that the Silurians (led by their relatively peaceful leader) would wake in time to help the humans find a way of fleeing the planet. Perhaps the crisis of both species of Earthlings in peril of losing their planet (of which the Silurians are clearly exceedingly fond) will help forge the alliance necessary for the lizards and apes to cooperate (and flee together, if necessary).


 * That's a great idea. No matter what Elliot Northover does, there would certainly be people who resisted the idea of the sharing the planet. But if the only choices were sharing the planet or fleeing on starships--problem solved.


 * Of course that erases the history behind both The Beast Below and The Ark in Space--but that's OK, because history can be rewritten. (The Doctor even says it's "in flux" in this episode.)


 * The Silurians were able to survive the heat near the mantle. They may have the technology to stop the solar flares from heating up the earth. They may also help the humans move underground.


 * According to Warriors of the Deep (Fifth Doctor) the Silurians do revive before the 1000 years, when the world is on the verge of war between two power blocs. They plot to destroy the 'apes', with the help of the creatures called the sea 'devils'. To answer myself, those beings are very different from those in Cold Blood and possibly represent an earlier stage of evolution. Different species of human have after all coexisted with one another (Neanderthal/Sapiens sapiens). Or perhaps the events of Cold Blood have established a parallel timestream in which the events of Warriors does not occur.


 * If nothing else, the Silurians/Sea Devils seen in Warriors of the Deep are obviously not the same individuals here. They're from a "different branch of the species", as the Doctor said. So those events could well have still happened while the colony seen here was peacefully slumbering away for another 1000 years.


 * The shard and the TARDIS don't match. On the TARDIS the sign is on top of the wood within the panel. But the shard shows the sign to either be in an indent or the panel to be much smaller.


 * We don't know for sure that the fragment was from the TARDIS and not just a genuine police box. Maybe its a fragment from a slightly differently designed Police Box?


 * To save the trouble of Amy forgetting Rory, why didn't the Doctor and Amy drag Rory in to the TARDIS to save him being erased from time?


 * If he dragged Rory in then Rory would always be dead. By keeping him and and letting him be erased there is the chance that Rory will be saved when the Doctor saves the universe. This is perhaps "hoping for the best" for the Doctor, as at the time he doesn't understand the cracks fully nor has he figured out about Big Bang 2.


 * His body was already being consumed by the energy. Amy attempts to drag him, and the Doctor tells her there's nothing they can do. Being caught in the temporal energy presumably made it either too hard or too dangerous to physically remove his body.


 * Also he didn't want to risk getting touched by the time crack's energy an being erased himself.


 * Nasreen appears to think 21,009km is the deepest part of the Earth someone has burrowed to, but in the events of Inferno the project achieved a distance much deeper than 21km.


 * Nasreen presumably is unaware of the Inferno Project. It was likely classified given the nature of the events that occurred (UNIT has a history of hushing up such things).