Sherlock Fall - Massive Spoliers Throughout

[Kythia]

So, I know there are some fans of the BBC Sherlock adaptation on here.  Just spent the day watching series two again and noticed something I hadn't previously:

Sherlock // The Fall

Rather rubbishy video but shows what I want.

Look at 1:17 Shot of the right side of Sherlock's face - St Paul's in the background.
Look at 2:14 Shot of the right side of Sherlock's face - entirely different building in the background.

I'd always figured from the fact he threw his phone away that the conversation with John wasn't happening when we thought it was - that it was a recorded conversation (he doesn't actually answer any of John's questions and sure he follows the same conversation as John but I don't think its unreasonable that Sherlock can predict John's thoughts.  He can in the books) and this seems to back that up.

I know this was discussed to death when it was first released but a quick google of some obvious seeming terms hasn't shown up any mention of that discrepancy.

[Oniya]

God, that's amazing.  I don't even think Michi picked up on that, although I had to look up pictures of St. Paul's to make sure it didn't have spires next to the dome.

[Stella]

....I did not pick up on that at all. I was too busy wrestling with the impossibility of spongy concrete and a body swap. Thanks for this, Kythia; given me a lot to think about!