So let me get this straight: Everypony's out of character in some trivial way, and that turns into a series of coincidences to create a situation where everypony believes that everypony is out of character in a more fundamental way? Really, they all should have realized that something more sinister was ahoof, not go and just reflect on how they are still all friends despite some hiccups.
Twilight especially should not have taken credit for the Fake Twilight's actions. Real Twilight might have stopped Pinkie from having her own fun (and even then "if we keep stopping" suggests that the problem is not the distraction but the excess of distraction), but Pinkie readily accepted Twilight's reasoning, so there was hardly any sign that that would be a source of friction between the two (or anypony else) in the end. She barely got "carried away." And Twilight, you and your friends have been through a *lot* worse. Don't fool yourself.
For a mid-season finale, it sure seemed an exercise in triviality. Beyond the triviality of the moral and the questionable development of the both the plot and moral, how I would have loved to see Chrysalis be destroyed by her own creations, or at least severely disabled/turned into a tree etc. (since there is supposed to be no death on the show). How I would have loved to see the Mane 6 even get a glimpse of Queen Chrysalis even for a moment, perhaps to symbolize the source of their own internal misunderstandings of each other, however temporary. But no, it's just an episode about fighting on the way to a camping retreat, one that fails to use its symbols to the fullest or even bother to create any real tension.