These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Rainbow Factory
Adaptation Displacement: An increasing number of people know about this fic through the Rainbow Dash Presents parody, to the point of accusing Aurora Dawn of ripping FimFlamFilosophy off. FimFlamFilosophy is trying to rectify this by crediting Aurora Dawn every time his characters are used in other videos and linking to the original fic on his blog.
Canon Defilement: Big time. What Cupcakes does to Pinkie Pie and Sweet Apple Massacre does to Big Macintosh, Rainbow Factory does to Rainbow Dash.
Complete Monster: Rainbow Dash oversees the murder of ponies every day, but what firmly rockets her into this territory is how she's implied to murder Scootaloo, the closest pony she had to a little sister, in cold blood. It's explicitly stated that Scootaloo's failure at the flight test, sealing her fate, kills the last kind feelings Rainbow Dash had and irreversibly turns her into a merciless monster.
Score another for Hilarious in Hindsight. The song, by virtue of not elaborating on the exact nature of for-mentioned 'fears and horrors', is quite compatible with the 2013 horror movie The Purge. To an extent, the fic is comparable for the shared plot-devices that the main targets of the murders are the less desirable parts of the respective societies (the poor in The Purge, the weak in RF) and that it has at least been suggested that they harvest the bodies from The Purge for power or some such thing.
Narm: Considering that the basic premise is essentially "Soylent Greenis PONIES!", it's liable to cause a few snorts if you refuse to take it seriously.
Every single adult pony they meet being EXTREMELY cruel to our three heroes.
Visual Effects of Awesome: The animation of both PMVs is extremely impressive, particularly the "Cloudsdale Weather Corp" screen at the beginning of the "Awoken" PMV and the slow-motion shot where H8_Seed bucks Brony Dance Party off the ledge.