Moffat-Era Tropes: Seemingly evil monster that really just wants to be told “good job, sir”; mummies; “are you my mummy?”; improbable things in space; character singing song; gratuitous, not always effective, celebrity guest stars (Moffat's not the only offender, but his era hasn't shied away from it); ancient myths that are actually real; ancient tech malfunctioning and causing fatalities; aliens targeting specific people; the Doctor sacrificing people in order to save others. This season's running obsession with soldiers is, well, soldiering on.
A Thing in a Thing: A mummy on the Orient Express, what else?
The Doctor is A: Nosey Parker. And Doctor of Intestinal Parasites.
The Master Is A: ...way. Gus is filling in for her this week.
Clara Lies About: the real reason the Doctor wants her to bring Maisie to the lab, and, for once, gets called on it. She then lies to Danny about having left the Doctor, and to the Doctor about Danny being fine with her traveling in the Tardis, but doesn't get called on it. Yet.
Reasons Clara Should Drop Danny Like A Hot Potato: Because he's clearly jealous and possessive, but denies it all over the place.
Child Count: Zero, this week, just to give us a break.
The Thick of It: Clara suggests the Doctor is addicted to power.
It's Actually About: Difficult choices.