Theory time!

I get the feeling that every single end-of episode element will somehow tie into the finale of the season. Which means the end of season four will somehow tie together the box from Princess Twilight Sparkle, the Pony of Shadows, Rainbow Dash's advance copy of Daring Do and the Rings of Destiny, Spike's disappearing comic, Fluttershy's fangs, Rarity's Spool of Rainbow thread, and no doubt several other objects to come.

Long story short (too late), keep an eye out at the end of each episode, guys. There might be something important.

Rainbow Dash is main Character?

Rainbow Dash is main character.