Theory:Doctor Who television discontinuity and plot holes/Death Is the Only Answer


 * When Albert Einstein turned into an Ood he had a translation sphere in his hand; if Einstein's liquid had transformed him biologically into an Ood, shouldn't he have had a hind brain rather than the technological replacement?


 * The change from Einstein to Ood could have been a timey-wimey substitution rather than a biological transformation; Einstein's timeline could have been replaced with that of a technologically-augmented Ood. The liquid having timeline-affecting properties would make sense, since Einstein had made it for his time machine.


 * Einstein might also have swapped places with an Ood which had been elsewhere in the universe; in this case the Ood wouldn't have been Einstein, just a regular red-eyed technologically-augmented Ood (in Einstein's clothes, somehow.)


 * The Ood's eyes are glowing and it's hostile; judging by what we know about the Ood, that would imply it's under someone's psychic control. Who would have been controlling the Ood and directing it to attack the Doctor, when it had instantly and accidentally popped into existence aboard the TARDIS?
 * If we go with the theory that this Ood had replaced Einstein in the timeline, any number of people could have been controlling the Ood in that time, psychically manipulating it towards an unknown goal. Or maybe its eyes were glowing because it's been technilogically augmented and popped into existence on Earth, and it attacked the Doctor out of confusion and fear at this abrupt change in circumstances/a defense mechanism.