I still don't understand the deal with the sisters. Why did the older sister disappear and why did she come back and why did Mab Arden have magic powers and what effect if any did she have on the trees?
I keep wondering if anything in the episode happened in reality, if any of the characters (including Clara but excluding the Doctor) were even real. There are so many problems with the episode's reality that a giant holodeck simulation seems to be the solution.
Why was London so depopulated? I find it difficult to believe that
absolutely no one was wandering around exploring the forest. For that matter, London is a major metropolis, and it never sleeps. There would've been people on the streets doing stuff and going about their lives as the trees appeared overnight. Some people would have witnessed the arrival of the instragrowth trees. Some people would have been surprised to wake up to the trees, while others would've been woken up by their neighbors going batshit insane because they saw it happen.
What about the cars and infrastructure? Where did it magically go? Buildings still existed, as we saw, but the trees seemed to fill up the streets. What happened to the cars that were on the streets? What happened to the cars that were in motion on London's streets when the trees appeared? Were there absolutely no car accidents from the instant trees?
The oceans! Somehow, trees grew on the oceans. How?
More importantly, what were the trees attached to? Did they actually have root systems (which would have destroyed sidewalks and paved roads), or were they like creeping vines that grew on top of the surface?
By the point the girl appeared in the magical bush, I had been so utterly beaten by the episode that I didn't care any more.
"In the Forest of the Night" is offensively stupid.