Review of Last Christmas
Warning: This review contains episode-specific spoilers and wild speculation about future episodes.
Santa Claus has absolutely no place in Doctor Who. Except when he does.
I will freely admit that I was among those fans who cringed and gnashed teeth when Santa showed up in the TARDIS at the end of Death in Heaven. The whole idea that this mythical (if well-beloved) person should exist as an entity as real as the Doctor himself within the Whoniverse just gave me hives.
The comedy-rich pre-credits sequence was, thus, painful to watch (though I do love to see Dan Starkey wearing his own face for a change). And on first viewing, Clara’s declaration that she does indeed believe in Santa Claus just adds the cherry to the top of the whole saccharine mess.
After one knows how it all pans out, though… Well, it all fits together nicely.
Note, for starters, that the Doctor never gives Clara an answer when she asks with breathless wonder if being back in the TARDIS with him is real. Combine that with his face-off with Santa before joining her there (“I know what this is. I know what’s happening. And I know what’s at stake.”), and I think it’s hard to argue that he’s not completely aware for the entire episode that they’re all dreaming.