So who needs lots of guns when you've got acid?
"Are you thinking what I'm thinking?" "Inevitably."
"Okay, I'm glad you solved the problem of 'confusing' "
"You know, I'm getting a sense of how awesome it is to hang out with me."
The choking-gas sequence doesn't seem to serve any purpose other than just to move the plot along.
"No offence. Being almost the Doctor is pretty damn impressive."
"Are you crazy?" ... Amy, you've been hanging out with the Doctor for a couple of years now, and you still have to ask?
So Rory's Jennifer is a ganger as well. Wonder how that works.
That wall of eyeballs was a bit of a non sequitur.
"Call me Smith. John Smith." That would have been a bit more of a statement of identity apart from the non-ganger Doctor if the Doctor himself hadn't regularly called himself that...
"If you have a better plan, I'm all ears. In fact, if you have a better plan, I'll take you to a planet where everyone is all ears."
"There was stuff and... shenanigans. Beautiful word, 'shenanigans'."
But for all the running around and drama this two-parter didn't really hang together very well. I'm seeing similarities between this and another rather lacklustre two-parter, The Impossible Planet / The Satan Pit. Both of these have a lot of good ideas padding out the old faithful "base under siege" plot, but both serials could have done with a bit of rewriting, a bit of refinement and a bit more clarity.
All this really goes to show is that giving an episode a title very close to the title of the best Doctor Who novel ever still isn't any guarantee that the episode will be any better than rather average.