I'm going to say that this one was a real standout in terms of one-liners. G.M. Berrow really has a knack for those, it seems (one of my favorites was Dash's "I know the bar is set pretty high, but...")
In fact there was an awful lot of self-awareness going on, the kind that I remember really endearing the show to me early on. On one hand the episode is moving along nice and slowly, and Twilight and co. are being complete thickheads about the scavenger hunt clues—and then, basically simultaneously, a) Pinkie flips out about how slow they're being and hustles them along in the same way an impatient adult would hustle a recalcitrant kid through a reading lesson, and b) Twilight points out that there's no time limit so what's Pinkie so freaked out about.

Really felt like the narrative was operating on two distinct levels.
Other standout bits I loved:
- SA and Mr. Cake high-hoofing
- SA's horror reaction upon discovering the burned comic book—right in the middle of that high-speed joyous montage, oh man, that montage was the best, I love how it was timed
- Moustache-and-glasses pony (with moustache-and-glasses cutie mark)
- Tree roots in the castle ceiling; Pinkie even hid among them
- Pinkie had an apple in her mane, and also she tripped backwards over her tail at the

shop
Now, a lot of these are animators' gags rather than writer's gags; but I like that that shows the animators are still as invested in keeping things fresh as they ever were. (The CMCs have their cutie marks now, but their role in the episode didn't hinge on them at all; this episode could have gone anywhere in the viewing order, and all it would have taken was a few seconds of footage re-rendered.) But Berrow's script showed a lot of that two-level energy, like Rarity pointing out (after we all would have noticed the same thing) that Twilight's design choices are, well, a bit juvenile, but presumably she knows what will tickle SA. It lets the show be naïve and shrewd at the same time, in the best tradition of S1 pony.
One other random note: Was this the first time we've heard the name Mayor Mare in-show?