This episode is intentionally similar to "Green Isn't Your Color", where Twilight has to keep a secret.  FOREVER!

Glasses on Fluttershy's tail. I'm guessing they thought it would be inappropriate to put them on the rump. which is how you usually do that joke.

I could NOT understand the end of this line so I looked it up in the transcript:

Quote

Pinkie Pie: Mine too! Baby carrots are kinda like big carrots but smaller, kinda like how foals are tiny versions of their parents but smaller and cuter and— Albino squirrel!

They were obviously trolling us with Applejack's birth certificate.

And I thought the part where Pinkie fell apart at the end was pretty disturbing.