Okay, I'm going to cut this, on top of all the wrong information that I have no idea where it came from, the "Friendship Express" DVD actually has the uncut version of the episode, so it's more of a case of being edited for TV and Itunes.
"The famous (or infamous) My Little Pony: Friendship Is Magic episode "The Last Roundup" featured Derpy Hooves (a fan-favorite background character) getting a brief but plot-important speaking role in the episode, including the fan nickname being used by a main character. However, some found her offensive toward mentally-handicapped people, somewhere between the name ("derp" being an Internet-borne pejorative) and the boyish voice given to her, so Hasbro briefly removed the episode from circulation and video purchasing services, edited the scene to remove the name drop, removed the wall-eyed expression that made the fandom notice her in the first place and redid the voice into one more Valley Girl-ish, and used that version of the episode from then on. Thus, the original airing of the show could be considered this."
I've read some posts several years ago (before I discovered this site, even) that the comment on "Special Ed" might have been posted by someone hacking the creator's account. I don't know, the whole thing sounds fishy to me, based off of just the name and the "too real" comment that sounds more like a hoax than an actual scrapped episode since Ed, Edd n Eddy never struck me as the kind of series that would have what seems like a Very Special Episode which references Special Education.
The other two episodes sound perfectly legit, however.