[ykf566]

Originally Posted by Wilfriback

Spoiler for The original anime stuff from J.C.Staff::

-Saten and Uiharu meeting Mikoto in the beginning.
-Urban legends thing.
-Invisible girl.
-Tokiwadai Garden.
-Asphalt girl.
-"Computer parts".
-Random guys who were owned by Kuroko.
-Saten's power
... I can't remember anymore for now.

The special chapter (assuming it was written the author) did say they were going to reveal Saten's power and more on garden inside the city, so i assume those are inputs from the author.
I seriously doubt it was J.C.Staff which just randomly came up with Saten's power, and Uiharu's too