A very refreshing episode after a season full of merely enjoyable mediocre episodes. There are only two things I didn't like about the episode:
1. All of the scientists who weren't main characters were blatantly extras and it really stood out that they were only there to fill in space. All they did were gape at The Doctor silently and blandly "doing science-y stuff" (what exactly were they examining with test tubes and stuff? They didn't have samples of, well, anything).
2.
I probably sound pretty nitpicky, but aside those two problems, I really did enjoy this episode. The aesthetics of the train, the twist on the Christie tale (although as someone else said, alas, no David Suchet), Peter Capaldi's continuously astounding performance of The Doctor as a heartless bastard, the new jazz version of "Don't Stop Me Now," Frank Skinner, "Are you my mummy?," jelly babies in a cigarette case, and the physical appearance of the mummy (Mary Whitehouse would've had a heart attack!).
1. All of the scientists who weren't main characters were blatantly extras and it really stood out that they were only there to fill in space. All they did were gape at The Doctor silently and blandly "doing science-y stuff" (what exactly were they examining with test tubes and stuff? They didn't have samples of, well, anything).
2.
I dislike the new tendency of important things happening off-screen. I would have liked to see how the Doctor got Clara to agree to one last adventure or how Clara came to that decision (I'm unclear how that worked, had trouble understanding all the dialogue). And of course, that we didn't get to see the rescue of the passengers. Then again, it's quite possible that the Doctor lied and he only managed to rescue the three of them.
All of this. Aside from looking absolutely gorgeous in her jazz-era dress and hairstyle, there was no need for Clara in this episode after her excellent meltdown at the end of "Kill the Moon" (one of the few good things about that episode). As Count Zero said, this episode broke the "show don't tell" rule and it was really frustrating having her have a sudden change of heart (twice!) with little to no explanation.Frankly, I think I would've prefered if we saw Twelfth in a Clara-free episode before this one. I dunnot, but I think this came too soon after the whole Kill the Moon thing for her.
I probably sound pretty nitpicky, but aside those two problems, I really did enjoy this episode. The aesthetics of the train, the twist on the Christie tale (although as someone else said, alas, no David Suchet), Peter Capaldi's continuously astounding performance of The Doctor as a heartless bastard, the new jazz version of "Don't Stop Me Now," Frank Skinner, "Are you my mummy?," jelly babies in a cigarette case, and the physical appearance of the mummy (Mary Whitehouse would've had a heart attack!).