- Alternate Character Interpretation: Were the Toclafane naturally that evil before they were converted into what they are now? Or did The Master butcher their minds as thoroughly as their bodies? Keep in mind that the last time we saw them, they refused to immediately resort to lethal force with the Futurekind and settled for scaring them off. It wouldn't be out-of-character for The Master to "cheat" to break The Doctor's spirit in this fashion.
- Angst? What Angst?: Humanity failed to evade the death of the universe, instead turning into the grotesque, murderous Toclafane as a last-ditch effort. Neither the Doctor, nor Martha, nor even the writers show much distress at this revelation, which is never brought up again. Though, to be honest, it's been a year of total hell, there is only so much despair one can take before they just stop caring. Plus, you have to admit, it's pretty impressive that humanity survived until the very end of the universe itself. Of course, it'd be even more impressive if humanity had managed to keep its morality to the very end instead of having every single human turn evil.
- Broken Base: This episode marks a shift from the Tenth Doctor being depicted as someone who was vengeful deep down and willing to consign his enemies to a Fate Worse than Death if he felt they deserved it, to being much more an outright Messianic Archetype. Fans are divided between those who felt that his previous depiction was too dark and/or too much like the Seventh Doctor and so welcomed the change in direction, and those who felt that it made the character less interesting.
- Esoteric Happy Ending: This is easily the happiest ending of any season of the RTD era. It wouldn't even be all that esoteric if it weren't for a few "little" things like, Martha and her family and everyone on the carrier still remembering this traumatic, PTSD-inducing year; America lost its President (and despite being intended as an unflattering Expy of George W. Bush, he still came across as a basically good man who didn't deserve to die); Britain lost its best political minds when the Master gassed them all to death; and also lost a good, courageous woman who tried to stand up to the Master only to get tortured to death by the Toclofane. And speaking of the Toclofane, it turns out that the final, definitive fate for humanity is that in the final generation, all the humans (even the best of them), will within that generation degenerate into monstrous, childish thrill-killers, making everything on the show that has anything to do with humanity feel completely pointless.
- Everyone Is Jesus in Purgatory: The Doctor has a lot of messianic moments throughout the series, but gaining power through faith had some overtones.
- Hilarious in Hindsight: The Master views being "kept" and rehabilitated by the Doctor as a Fate Worse than Death. In series 10, this is exactly what happens to his next incarnation.
- Narm: The Master using Rapid Aging to somehow turn the Doctor into Gollum and Dobby's freaky love child came across as downright ridiculous to quite a few viewers. But many more, including most members of the first group, felt that the episode then managed to top that moment in absurdity by having the Doctor then turn into what can only really described as Tinkerbell Jesus in the climax.
- Martha's gloating about how the gun with parts all over the world was so obviously absurd that the Master is a fool for falling for it would be epic... if it wasn't immediately followed by the reveal that the real plan was far, far more ridiculous.
- Retroactive Recognition: Tom Milligan is Lucifer.
- Ugly Cute: The Doctor in his most aged form.
YMMV / Doctor Who S29 E13 "Last of the Time Lords"