Jerkass Woobie: Applejack's stubbornness and arrogance lead her to work herself into a disoriented wreck, causing a lot of collateral damage in the process. By the end of the episode, her strain and symptoms become unsettlingly realistic (if still humorous) and you end up feeling for her when she reaches the point where she doesn't just cave in to Twilight's offer but outright begs for it.
Pinkie Pie should have known better than to cook the "baked bads" using the wrong ingredients (especially earthworms instead of wheat germ) considering she is a professional baker!
Applejack really should have rested if she wanted to succeed in her work, which she learns the hard way, doubling as an Accidental Aesop.
The Woobie: Subtle and (most probably) unintentional, but right at the end of the episode Applejack says to the other main cast: "But the real award is having you five as my friends." Right at that moment Spike walks into the frame, and you would expect Applejack to acknowledge him too... but she says nothing.