- Fake Irish: For whatever reason, Spike talks like he's from Scotireland.
- Keep Circulating the Tapes: While the pre-reboot episodes were removed from Greg's channel, they can be found elsewhere on Youtube, some places with his blessing, others not. A fan also remade the original Episode 12 in a Rainbow Dash Presents-esque style artwork.
- Missing Episode: Episode 11, which was meant to be the parody of "Fall Weather Friends", got stuck in Development Hell and was eventually cancelled. This is because Greg ran into difficulties trying to make the episode funny. Eventually, after about a year, he simply gave up and went straight into parodying "Suited For Success", labelling it Episode 12 (to satisfy his numbering style) and including a rapid thirty second montage from "Fall Weather Friends" at the beginning so to acknowledge its existence. Episode 11 has only been shown twice once during a livestream, and once at a con is incomplete, and about 6 minutes long.
- Episode 23, scheduled to release the day after the channel received the ContentID claim that led to the switch from screencaps to original art, was screened at the same con (years later, of course). Unlike Episode 11, it is complete although the camrip version of it posted online by a 3rd party with Greg's permission lacks the usual rambling end credits, and any background music it may have had is not audible.
- Promoted Fanboy: Petirep started off as just an artist who loved Mentally Advanced. He drew a few pieces of fanart that Greg saw and liked enough to feature in the show's end credits. Not long after, Greg contacted him and asked him to draw a few dozen simple pictures for Rainbow Dash Presents: Bubbles. Since then, he's become Dawn Somewhere's go-to artist, creating the site's logos and even filming some tutorials for aspiring artists, all while continuing to occasionally produce Rainbow Dash Presents and sometimes his own fake vlog series, DinkySharkFighter32.
- Kenza, who plays most of the series' male characters, is a Danish girl who was also a big fan of Mentally Advanced and Rainbow Dash Presents. When Greg fell out of contact with the original girl he used for voices, Kenza got in touch with him, and he cast her as The Jokermort. During production, they hit it off and eventually started dating — quite a feat considering she's in Europe and Greg is American. She now voices every male character in the series (except for Big Mac and Spike, of course).
- Talking to Himself: All the main characters are voiced by the same guy. The creator's friends Smeg and Allen voice Gilda and Celestia respectively, while his female friend voices Snips and Snails (and other male background ponies). His friend DeMarkus voices Thrackerzod and Aurora. Later, his girlfriend (later fiancee) took over voicing the male ponies.
- What Could Have Been: "Rainbow Fun Factory" was originally going to be much longer and have more singers, including Aurora. A stand-alone song featuring Aurora was later produced.
- The voice for Dazzler earlier in the episode was originally going to be provided by Jenny Nicholson of Friendship is Witchcraft fame, but she got offended at one of Greg's jokes during production and broke off all contact with him.
- Thrackerzod only came into being because one of the creators of Witchcraft decided to troll Greg's channel comments section (back when Youtube still allowed that to be part of a channel's front page), demanding that he include more Sweetie Belle in his episodes. He responded by insisting Sweetie Belle doesn't exist, giving a sneak peak of Thrackerzod quoting part of the Cthulhu Mythos at them. If Jenny and Griffin hadn't decided to mess with Greg right then, Sweetie Belle could have turned out very differently.
- These Tumblr posts describe where the show would have gone had Greg continued it.
Trivia / My Little Pony: The Mentally Advanced Series