Theory:Doctor Who television discontinuity and plot holes/The Girl Who Died


 * If the Mire are strong warriors and have a device that "repairs" them continuously, it's unlikely that they are frightened by a bad CGI monster (and when they see that the monster is not affected by their weapons, it's unlikely that they don't recognise their own hologram technology). Indeed, it's strange that the Mire don't rule the universe yet - or at least the galaxy - with immortality devices so cheap that every soldier has one in their helmets! (Ok, ok, we know for sure that at least two soldiers have them in the helmet, we don't know about other soldiers). The same thing could be said for the Chula, which we never see on screen, warriors that have nanogenes that cure everything and bring the dead back to life!
 * You answered your own question: The Mire don't rule the universe because there are other races, like the Chula, who have similar kinds of immortality to the Mire's. And others, like the Sontarans, or even the humans in a pinch, who can clone up more warriors faster than you can kill them. And so on. It's like asking why 1960s Britain didn't rule the Earth when they had Harriers—in a world with F-4s and MiG-23s, they don't dominate the skies.


 * Ashildr mentions corn, which only existed in the Americas at the time and wasn't imported to Europe until after the discovery of the new world.
 * In English, the word "corn" means "The main cereal plant grown for its grain in a given region, such as oats in parts of Scotland and Ireland, and wheat or barley in England and Wales." - the word corn actually comes from Old English. So the word is correctly used.
 * It's worth noting that this is true in British English, and therefore correct for the episode, but not for American English, so Americans aren't stupid for being confused, just being misled by the same kind of difference in vocabulary that causes them to wear their pants on the outside.


 * Electric Eels are native only to the Amazon
 * Both are correct but we don't take the real world into account here: http://tardis.wikia.com/wiki/Tardis:Valid_sources#The_real_world_doesn.27t_count
 * Although no one has brought it up yet, the above also applies to the fact that in real life Vikings didn't wear horned helmets as seen here.
 * Time Machines don't exist either but we can accept that for the narrative of the show.