As far as I can tell, the original 1984 special "Rescue from Midnight Castle" hasn't been released in unedited format since the VHS Children's Home Library version. Redundant cliffhangers are one thing, but whole songs are another. According to http://mylittlewiki.org/wiki/My_Little_Pony_Special, "a scene including the 'Little Piece of Rainbow' song had been edited out," aka Moochick's song.
The DVD release of Escape from Catrina edited out a scene with the song 'Those Good (Before You Turned Bad) Old Days'. The special originally had unique bookends. http://mylittlewiki.org/wiki/My_Little_Pony:_Escape_From_Catrina
Fact check any of this stuff, I'm just going by wiki pages. Is it possible to get a DVD version with the deleted scenes restored? If not, I'm guessing VHS versions have the original unedited TV specials.