Just throwing this out there. When the finale comes around, the journal they are all writing in becomes Twilight’s key, because friendship.

Just 4 more and we’ll soon get an awesome finale!

@Background Pony #D5F6  
How do you test for magic?

I admit I’ve figured out how to easily tell if an episode leads to a “key.” The episode is about testing a character’s element. Rarity’s generosity got tested by having it work against her, but in the end learned that just because some people are jerks and may take advantage of your generous nature doesn’t mean you should stop being generous.
 
Now here we had Rainbow Dash’s loyalty being tested between sticking with her original team so they can make sure Ponyville has representation in the Games, or join her hometown team that clearly have more talented pegasi (who double as childhood heroes… childhood heroes who let competition really go to their heads and can be unsportsmanlike in the face of an Olympics styled event, but still you get what I mean).
 
Soon enough we’ll get ones for Kindness, Honesty, Laughter, and Magic.

@falkon123  
That would be cheesy enough to just be true.

Pretty sure Twilight’s key will be the Friendship Journal.

@D50  
In which case we’ll need a total of thirty-six rainbow MacGuffins.
 
Mmm, Rainbow MacGuffins. Rainbows, Canadian bacon, and cheese on a plot-advancing English muffin.

Two down, four to go.

And now lets wait for next flutterbitch and appleliejack episode.

@igotnopicks  
Or they combine to make one key.

Four to go.

Two down, four to go.

we should just keep a running tally of the “keys” like this

Rainbow thread: hey rainbow medal! how was your premiere?  
Rainbow Medal: I GOT COMPLETELY OVERSHADOW BY SOME GRAY PONY! :(

Two keys.