Small Plot Point Revealed From DOCTOR WHO: "A Christmas Carol"?

In a New York Times interview, Doctor Who showrunner Steven Moffat might have slipped out a minor point about the ending of the upcoming Christmas special "A Christmas Carol".  It isn't terribly major and seems like a joke, but I'm giving a spoiler warning anyway.  So if you want to know, ignore River Song's spoiler warning below.

The interview read like there had been a press screening of the special, and the following was said regarding the ending:

Q:  Your “Doctor Who” episodes often end with teases to the next story line, and this one ends in an especially tantalizing way — or is it meant to be a joke?

A:  That’s just a gag. We’re not going to investigate the mysterious marriage of the Doctor and Marilyn Monroe. It just happened in the background.

Q:  Are you permitted to say what’s in store for the next season of the show?

A:  Well, I’m permitted to say anything I like. I just don’t. [laughs] We’re going to America, which we just shot out in Utah, for our opening two-parter. We’ve never done this before – we’re opening with a two-parter that starts in America during the ’60s.

The following exchange took place regarding the general feel of this year's special:

Q:  What was the genesis of this year’s Christmas special?

A:  There had been a feeling that we needed a really, really Christmasy one, because the previous one had been David Tennant’s exit from the role. It had been quite dark and not as Christmasy as normal. We had wanted to reset it and make it a hugely jolly, merry one. Well, jolly, merry and a little bit sad.

The episode airs on BBC America Christmas Day, and this is the first time a new episode has been aired on the same day in the US and the UK.  I hope that trend continues with Series 6 next year.

Here's the synopsis for the special:

"Amy and Rory are trapped on a crashing space liner, and the only way the Doctor can rescue them is to save the soul of a lonely old miser, in a festive edition of the time-travelling adventure, written by Steven Moffat. But is Kazran Sardick, the richest man in Sardicktown, beyond redemption? And what is lurking in the fogs of Christmas Eve?

Matt Smith and Karen Gillan return for an all-new Christmas special, along with Arthur Darvill and guest stars Michael Gambon (Harry Potter) and Katherine Jenkins."