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


 * It is left unexplained why Britain's space program has apparently reverted to celebrating unmanned probes arriving at Mars when The Ambassadors of Death established that by this time Britain had already sent manned missions to Mars.
 * There is actually a real-world example of such reversion occurring. America's NASA program sent manned missions to the Moon in the 1960s and 70s, yet by the 2000s had reverted to again sending unmanned probes to the moon. The secrecy involving restricting public knowledge of alien life might also imply that those earlier missions may not have been public knowledge.


 * In The Ambassadors of Death the Time Lords were still around. The Doctor could have visited a parallel universe, as it was still possible to do so at that time.


 * Time is constantly in flux.


 * After indicating to Rose how important Harriet Jones becomes to Britain and planet Earth in World War Three, the Doctor proceeds to sabotage her career. What about his many spiels about his being forbidden to change history?
 * Some events can be changed, as established in The Fires of Pompeii. This must be one of them. In any case, Harriet Jones was to be vital to the world in The Stolen Earth. In that story, her death was not witnessed by the audience or any of the characters. It remains possible then, that she survived and did eventually serve the two more terms and usher in Britain's Golden Age, as predicted by the Ninth Doctor. Alternatively, it was the Doctor deposing Harriet that led to to be elected in her place.


 * How is the scarf that the Fourth Doctor wore in the TARDIS wardrobe? The Fifth Doctor took it apart in his first episode, and the Ninth Doctor was noted on Clive Finch's website to throw a scarf into a skip.
 * It is possible that the Fourth Doctor had multiple scarves, just the Tenth seemed to have multiple blue suits.


 * The Doctor could have acquired a new scarf, or simply re-sewn the old one if he became nostalgic.


 * After dumping it in the skip he may have changed his mind and got it back.


 * Re-watch TV: Castrovalva. The Fourth Doctor was seen to wear at least two distinct scarfs. The Fifth Doctor unravels the Fourth Doctor's burgundy scarf. The one seen in the wardrobe here is multi-colour.


 * If the Robot Santas could plant the remote controlled killer Christmas tree into the Tyler's flat why couldn't they simply abduct the Doctor while they were there or if they planted the tree by means of teleportation why not simply teleport themselves inside?
 * Simple, the disguised roboforms are known for stealth. If they tried to abduct the doctor, they would probably have a difficult situation on their hands considering they wouldn't have any way to properly dispose of him. For the second point, though the roboforms have the ability of teleportation, it may be short-range and/or might not be able to traverse through walls.


 * Harriet Jones states that the Royal Family are "on the roof", suggesting that they are under the control of the Sycorax and are blood type A+. However the Royal Family are blood group O-, so would be unaffected by the blood control.
 * It was implied in Tooth and Claw that the royal family has slight amounts of alien blood from the werewolf, which could easily be A+ blood.


 * How is it that Harriet Jones and the translator can understand the Sycorax after the TARDIS translator started working again? Neither of them have ridden in the TARDIS, so it wouldn't translate for them as it would Rose and Mickey.
 * Because they are all so close to the TARDIS, it is possible that they would start translating.