About the only comment I have to make about this week's is the people who try to apply science to Doctor Who are going to flip their wigs over this one.
GOD.
That was possibly even worse than Kill the Moon. You can't just make up silly crap about Earth like that and have it work at all. Forests growing over everything overnight (and everything apparently disappearing to nothing more than the occasional lawn chair and fence, and even covering the entire ocean, and where the hell were the people?), and then have this giant solar flare directed right at Earth and be saved by flameproof trees, and the trees magically save Earth and disappear to nothing and have caused no damage to ANYTHING.
On top of that, the one girl who can somehow tell what's happening just happens to be in Clara's class, and just happens to be with Clara and Danny at the time on an overnight excursion. And yet again something bad happens right at Clara's time and place. Think about it, a lot of bad shit just happens to occur right around her.
And Danny saving them from a tiger with a flashlight (you brought a bunch of kids right up to a tiger?). And there were just too many kids in the episode.
And yet again, The Doctor had no damn clue what was happening and didn't know this had happened before, and humanity were just going to forget that a giant forest appeared and disappeared overnight, in the age of the internet where even the kids were taking selfies to document it all. That is the lamest cop-out reasoning.
We didn't need another episode of The Doctor being clueless, helping them to do nothing, and everything magically sorting itself out and being beyond bizarre and believable. We also didn't need another episode on Earth, in London, in the present day, that centers around Clara's school. Enough of Clara and Danny's small world already. There's an entire universe of time and space out there to explore!
Kill the Moon, Robot of Sherwood, and this week's episode were easily the worst of the season, with the rest being great. At least the finale is looking amazing, so I can't wait for that. If the finale is as good as I hope, it should really round out this season nicely.