Theory:Doctor Who television discontinuity and plot holes/City of Death


 * It's very unlikely a Human could withstand the earth's atmosphere 400 million years ago, yet Duggan, the Doctor and Romana don't have a problem standing outside at that time.
 * Duggan, maybe would have a problem; the Doctor and Romana being Time Lords likely wouldn't. Another possibility is that the TARDIS was protecting them as well.


 * How does the Doctor twice manage to direct the TARDIS to a specific point when the randomiser is installed?
 * The sentience of the TARDIS has been long established, too, so it might have known to bypass the randomizer.
 * The Doctor does have the capability to bypass the randomiser if he chooses to do so.
 * So why not just say so in the story? Especially since this is one of the very few times up to this point where the TARDIS has landed exactly, dead-on where the Doctor wanted to go.
 * Who would the Doctor tell? Romana, who would already know he can do it, or Duggan, who doesn't know anything about the TARDIS or the randomiser in the first place?


 * If the Countess has managed to go her entire married life without discovering that her husband is really a cycloptic, green-tentacled alien then either his skin suit is incredibly sophisticated to hold up to such intimate scrutiny, or their marriage is unconsummated.
 * Both are possibilities. It was only ever a marriage of convenience, and some aliens [including the Slitheen] have been seen to possess the ability to use "fully functional" human bodies as disguises.


 * Also, she's an upper-class British woman who married a rich continental Count because of the gifts he bought her. How much intimate scrutiny is involved in lying back and thinking of England while doing your wifely duties under the covers with the lights off?


 * Alternately, given the mores of time, she may have willingly entered a sexless marriage, assuming the Count was gay.


 * It might not be irrelevant to note that the Egyptian papyrus suggests that Scaroth isn't scaly and green all over his body.


 * Life had already started 400 million years ago.
 * Maybe in the Whoniverse, the Silurian extinction event was more complete than in ours, and life had to be restarted. Or one of the earlier extinctions. Or the Time Lords sterilized the Earth 2 billion years ago because they predicted humanity would become a threat. Or life just never started naturally on Earth in the first place. Or whatever. Remember, the Whoniverse is not our universe—a planet that formed around the Racnoss spacecraft might not be exactly the same as one that formed through natural planetary formation, and the fact that it just happens to look pretty similar in 1979 could just be coincidence or convergent evolution or morphic fields or whatever.


 * In episode four Romana wires up a British three pin plug in order to connect Scaroth's time equipment to the (French) mains.
 * She has an adaptor handy; she's just more used to wiring British plugs.


 * In episode one, the wrist of Scaroth's monster glove flaps about.
 * It really is a glove if the Egyptian papyrus is to be believed.


 * The sketch of Romana is different when it's seen outside the café from the one seen inside (and just who's doing the sketch, and why?)
 * To answer your second question first, in Paris, artists tend to sketch punters in public places if they look visually striking. Also we saw the artist sketch Romana twice, so there was every possibility that as the two moments equalized, the 2 pictures became one, and it ever so slightly changed the way it looked, because he may have drawn it slightly different each time.


 * The chances of there being solid land for them to stand on Four hundered million years ago are very unlikely.
 * Why? The Earth in the Devonian period had about 50-80% as much land surface as the modern world (although ironically, back in the 1970s, some people still believed it was a greenhouse drowned-earth age), and much of that land was part of large continents just as it is today.


 * Trapped within a bubble of accelerated time, without food and water, the chicken should just die before it has a chance to mature. Kerensky would not have time to reach old age before dehydration set in, either.
 * It is stated that anything in the bubble moves backwards or forwards in its "life cycle". This may just mean that it grows older or younger rather than literally living out its life faster.


 * Scaroth's device to refract the security lasers causes them to bend into the wall. Since this would still result in breaking the beam, it would set the alarm off as surely as sticking a hand between them.
 * We don't see the actual theft but a holographic "dress rehearsal". Presumably, the Count noticed this then and made an adjustment for the real theft.


 * Not one of the cafe customers even blinks when gangsters hold guns to the Doctor, Romana and Duggan nor when Duggan has a gun out.


 * After writing "this is a fake" on all the canvases, how can the Doctor be sure Scaroth won't come back and see them before Leonardo paints the copies? Especially since the Doctor has left. He wouldn't have just left without doing something to undermine Scaroth, and Scaroth would know it once he got done with his timey-wimey trance.


 * How did Scaroth create his "Mission: Impossible" rubber masks in the 11 historical eras before modern prosthetics? Why did he always choose the same face?
 * Considering he can rip it apart multiple times and it can cover his real head which is bigger than his fake one, I think its safe to say that whatever the mask is its a lot more complicated than a "rubber mask". How he created it is unclear, perhaps some of his technology managed to survive the explosion and was in a good enough shape to jerry rig. He was after all able to create solid holograms with 1970's technology. As to why the same face, considering how alien he truly looks, perhaps it was simply easier to reuse the same template.


 * Scaroth's machine only travels in time. When back 400M years ago, how does he get from pre-historic Paris France to pre-historic "the middle of the Atlantic Ocean" (according to the Doctor) in the two minutes Romana's rig-up lasts? And on that subject, why did she rig it up for only two minutes? At the time she was working to actually help Scaroth (as evidenced by the fact that she tried to persuade the Doctor to help him).
 * To answer the last question, Romana set the machine to return Scaroth to the twentieth century because she was concerned about him becoming trapped in the pre-Cambrian if his attempt to stop the ship's explosion failed.


 * How can Leonardo da Vinci paint 7 exact copies of the Mona Lisa without any at least subtle differences that a modern art authenticator couldn't distinguish?


 * In part three, Romana mentions to Duggan that she is one hundred and twenty-five years old — yet her age was given in The Ribos Operation as one hundred and forty.


 * Perhaps she's simply lying about her age!?