^What do you mean about liberties being taken with locations?
Sean Pertwee as Lestrade! Awesome! They called him "Gareth" here, which is new; canonically, he's simply G. Lestrade. (He was Giles Lestrade on BBC Radio and Greg Lestrade on Sherlock
, although that version seems to be an amalgam of Lestrade and Gregson.) And they referenced "The Adventure of the Norwood Builder," which was indeed one of the stories Lestrade was in.
My problem is, I grew up with the Granada Holmes series pronouncing "Lestrade" with a long A, rhyming with "trade," so I've come to think of that as the way it should be pronounced (after all, he's English, not French, so it makes sense that the pronunciation would've been Anglicized), and the French-style pronunciation that every other production uses, rhyming with (the American pronunciation of) "trod," always sounds wrong to me.
I'm more lukewarm about Mycroft. I don't get why the modern Mycrofts have to be so... thin. At least this Mycroft was formerly obese, and possibly formerly lazy as well, though that seemed more like Sherlock being hurtful. But I suppose the subplot of his attempt to make amends with his brother fit the theme of the episode. I guess Rhys Ifans doesn't do much for me as a performer.
Nice that they actually shot in London -- though I think the 221B interior was a stateside set, since Joan looked greenscreened in front of the window.