Theory:Doctor Who television discontinuity and plot holes/Time Crash


 * If the Tenth Doctor recalls this meeting from when he was the Fifth Doctor, then why was the Fifth Doctor so worried about his regeneration in TV: The Caves of Androzani?
 * Perhaps in the heat of his impending "death" the Fifth Doctor simply forgot about his future encounter or perhaps time was in flux (as many episodes have established that regardless of the historical record, it's still possible for the Doctor and others to die if they aren't considered fixed points in time). There also seems to be a strong suggestion that the ringing of the cloister bell triggers the Tenth Doctor's memories.
 * The Fifth Doctor portion of AUDIO: Peri and the Piscon Paradox, set immediately before The Caves of Androzani, but written after Time Crash, supports the notion that the Fifth Doctor has retained no accessible memories of meeting the Tenth, as he expresses to Peri a fear of meeting his future self (even though by this point he already has, assuming Time Crash does not take place in the midst of the events on Androzani, of course).


 * The Fifth Doctor is shown wearing the cricket jumper, coat, and dress shirt from Season 19 and 20 but his trousers are clearly the orange trousers from the Season 21 outfit.
 * It is possible that, for the Fifth Doctor, this episode takes place in between the change or that he was simply trying combinations when the TARDIS crashed into itself.


 * If the Tenth Doctor tells the Fifth Doctor about meeting the Master in that incarnation then he would have known that he wasn't the Last of the Time Lords (although this may partially explain the Doctor's extreme reaction to the news that Professor Yana has a Chameleon Arch fobwatch).
 * Possibly, because the Doctor met the Master several times after his Fifth incarnation, he assumed that the Tenth meant one of those other encounters (such as the TV movie, in which the Master has a wife and no beard). It's unclear how much of this encounter (if any) the Fifth Doctor retained, as it's suggested the Tenth Doctor remembered at the moment he heard the Cloister Bell.


 * The Tenth Doctor was at least as much confused meeting himself as the Fifth Doctor and he did not expect the Fifth Doctor thinking he is a fan (Although he should have remembered it).
 * It's unclear how much of this encounter (if any) the Fifth Doctor retained, as it's suggested the Tenth Doctor remembered at the moment he heard the Cloister Bell.


 * Throughout the story, the Doctor's hand-in-a-jar is located to the right of the console (as seen by viewers), but with the glass turned away from the camera (the illuminated interior can barely be glimpsed. It is in this position as Ten says goodbye to Five. Immediately after, the crash into Titanic occurs, and the hand-in-a-jar is suddenly positioned at the same spot on the floor, but with the glass facing the camera.
 * Surely the impact of the Titanic crashing into the TARDIS could have moved the jar, even if just a little.


 * Two episodes previously, in TV: The Sound of Drums, the Doctor claims that Time Lords can always recognise one another, and in that episode and the preceding TV: Utopia, he recognises the Master on sight (even after having spent a considerable amount of time knowing the Master only as his human form, Yana). However, in Time Crash, the Fifth Doctor does not recognise the Tenth.
 * In TV: The Five Doctors, the First Doctor does not realise who the Fifth is, although it doesn't take that much to convince him. The Fifth Doctor, however, instantly recognised his younger self; similarly the Tenth Doctor identified the Fifth without any delay. Clearly, there are some difference between meeting other Time Lords and meeting oneself.


 * When the Tenth Doctor asks where the Fifth Doctor is in his life, why does he only reference Nyssa and Tegan and not other companions, particularly Adric.
 * Perhaps he didn't want to cause any time-paradox issues by mentioning a companion the Fifth Doctor may not have yet met (Nyssa, Adric and Tegan travelled with the Fifth from the very start, but not Peri, Compassion or Turlough, for example). As for Adric, he presumably didn't want to remind his younger self of his death.
 * Although he asked the question, note he does so after the cloister bell appears to trigger his memories, so he might already have a sense as to where the Fifth Doctor is in his timeline (he could even just be making conversation).
 * It's also possible Ten is attempting to further cement in Five's mind the fact he is a future incarnation.


 * The presence of two Doctors apparently will create a Belgium-sized hole in the universe. This did not occur any other time different incarnations of the Doctor met (at least onscreen).
 * The damage is suggested to be in fact caused by the two TARDISes merging. Also, in The Three Doctors, The Five Doctors and The Two Doctors the meeting of the Doctors was at least partially orchestrated by the Time Lords, who may have been able to negate any such effects.


 * The revived series has expanded on the idea of the TARDIS being alive, and Jack Harkness (and possibly also the Meta-Crisis Tenth Doctor) has a quantity of "TARDIS coral" with which they can grow a TARDIS. In TV: The Impossible Planet, the Doctor confirms that TARDISes are grown and not built. The TARDIS's "coral" appearance is presumably meant to reflect this. However, this episode reveals that the coral look is only one of several possible "desktop themes".
 * Perhaps the coral theme is the default, as it was how the TARDIS looked when it was originally grown. Or maybe the default look is a completely different "organic" look that we've never seen before. Just because they are partly organic doesn't mean they have to look like coral. There has also never been an on-screen reference to "TARDIS coral" from Harkness or anyone else; a deleted scene from Journey's End (included in the Series 4 DVD set) shows the Doctor giving the Meta-Crisis Doctor a piece of the TARDIS, but it is never referred to as a coral and is never shown in great detail. The use of the term "coral" is an example of "fanon" -- facts made up by the fanbase and assumed to be canon over time, even though they have no on-screen confirmation.
 * Past episodes have also shown that the Doctor has the ability to change the look of the TARDIS interior - witness the numerous changes to the main control room between 1963 and 1989, and its transformation into a library-like room in the TV movie. (The "secondary control room" seen during the Tom Baker era doesn't count as it's clearly identified as a different room rather than a remodelling.)


 * The two Doctors address each other as "Doctor". Is the Doctor's name really such a secret that he can't even tell himself?
 * He has shown fondness for the term "Doctor" over the years, and would have no reason not to use it here. Alternatively, it could be that the Doctor does not ever want to utter his own name; as Steven Moffat suggested, there must be some "terrible secret" about the Doctor's name. In the Five Doctors, the Second Doctor addressed the Fifth Doctor as Doctor, too.


 * In at least two episodes, it's shown that a past and future version of the same person cannot touch without consequences. (the explosion in TV: Mawdryn Undead when the the Brigadier's selves touched, and in TV: Father's Day when Rose Tyler almost holds herself as a baby) yet Ten touches Five with nothing happening.
 * Time Lords are shown to be immune to this problem in the TV: The Three Doctors, TV: The Five Doctors and TV: The Two Doctors, at least when they are in different incarnations, it is probably something to do with the fact that, as the Sixth Doctor said, Time Lords are made for time travel.