Board Thread:The Panopticon/@comment-4028641-20151011010956/@comment-26469787-20151013111730

It's extremely likely that it's an explanation for the sake of Clara, either given by the Doctor prior to the story (and as such, why he references it at the end of the story) or an explanation of his reference. There is also the possibility he is explaining it to someone unknown, or that he is in fact breaking the fourth wall. But the potential for it being metafictional interaction is barely greater in this sequence than when any character speaks with no-one present.