WARNING! THERE MAY BE UNMARKED SPOILERS!
- Everyone in the world was turned into the Master. That means that, shortly before the Doctor met Amelia Pond, she was the Master! Her boyfriend Rory was the Master, her aunt was the Master... if they weren't yet swallowed up by the crack, both her parents were the Master... the Police kiss-o-gram outfit was The Master...The only ones who may not have been the Master is her good friend Mels, Mayor Me and Nardole....Even Clara was the Master! Indeed, as of "Name of the Doctor", lots of Claras were the Master.
- A lot of the Tenth Doctor's behavior and reluctance on wanting to regenerate gains a new light in this episode now that we know he had one more regeneration to use at the time, meaning he didn't want to regret becoming something worse and be stuck with it.
- The Master has the sound of drums implanted in his head as a child. That means every time the Master tried to "destroy" the human race, he was really trying to release the time-locked Time Lords — remember those times he used the Nestene Consciousness and the Autons? That would have had the same effect as turning them into "The Master Race"!
- The reason Wilfred was drawn to the Doctor was a complicated way of fighting fate. The Woman's dialogue implies that the Doctor was in threat of being killed for good, and that so long as Wilfred was with him, and gave him the gun, the Doctor would be able to survive and regenerate.
- The Doctor has two main sources of stress this episode: 1) regeneration will mean he will be dead while another man with his memories walks away, and 2) he's so old he's tired of living. But this regeneration only lived about five years in-universe, so these things can't both be true.
- The other man won't just have his memories, he'll have those of his previous selves too. Which reconciles this discrepancy: it's not his limited time as Ten that's making him feel old, but his cumulative memories of all the other Doctors he's been.
- Rassilon condemns the Woman and the other Council member who'd voted against the Final Sanction to stand as 'monuments to their shame', hands held up in front of their faces, "like the Weeping Angels of old". To what fate did the manifestation of Rassilon from The Five Doctors condemn would-be immortality-seekers? To be helplessly frozen in stone, also like the Weeping Angels of old!
- The existence of the War Doctor and confirmation the Meta-Crisis event counted as a full regeneration has retroactively added quite a bit of gravitas to Ten visiting his old companions and especially his last words. He knows that he is about to turn into what he expects to be his last incarnation ever and he knows that, buried in his subconscious, his supposed fate at Trenzalore is not too far off either, and it scares him. "I don't want to go" indeed.
- By the same reasoning as the above point, at this point the Doctor is on his twelfth life, and he already knows what is meant to happen to him "between his twelfth and final incarnations." Because of this, his "I don't want to go" response could be interpreted as fear of what he will become, not as the Eleventh Doctor, but as the Valeyard.
- Joan Redfern told the Doctor that John Smith was braver than him. "You chose to change. He chose to die." In this story, the Doctor chooses to die to save someone else.
- The Master's line "I wonder what I'd be without you" takes on a new meaning in light of the Series 12 finale.
