@Chilly Pepper  
They write the episodes so far ahead that they wouldn’t have been sure it would continue past the magical syndication number. This happened in all the later seasons of Stargate SG-1 - they wrapped things up, only to find after filming the final that they were renewed.

@JP
 
Twilight: Hmmm… I wonder what this does…
 
$> sudo rm -rf /
 
Celestia: Wait! NO! DON’T DO TH-

Celestia. MONITORS! EVERYTHING!

This particular sequence, if no others in this episode, made it feel like it could have been a series finale instead of a season finale.
 
^{Yes, I know that there is season four on the way, but it still felt/looked that way.}

Twilight: What is this place, really?  
Celestia: The borderworld. A control system for the computer-generated fantasy worlds. It was built millennia ago by bipedal race called humans. Very violent, but technologically advanced race. After conquering the space and figuring out the secrets of the universe, they got bored. They started to experiment with artificial worlds. And they created this. There are millions of worlds here. Hundreds of millions of worlds. Equestria is just one of them. The legend says the humans still exist, in some of those worlds.  
Twilight: …  
Celestia: And now you will be granted root access rights to the system. Use them well. Pinkie Pie is an anomaly we cannot explain, but you will now have higher access level than she does. Say hello to bending reality in any way you want.

*dark, not black

Reminds me of Black History.