WARNING: Untagged spoilers ahead. Read at your own risk.
- Actor-Shared Background: As confirmed by one of Thomas' tweets
◊ Elliott from Cartoon Therapy is non-binary and uses they/them pronouns just like their actor, Joan. Also from Cartoon Therapy, Kai has Ehlers-Danlos syndrome, just like the actor portraying him, Talyn. - Alternate Universe: Thomas Sanders has officially established one universe for the Sanders Shorts series and another one for the Sanders Sides series. In the Sanders Shorts universe, he has the Teacher Guy, the Dad Guy, the Prince Guy, several Anxiety Guys and other characters like Sleep, Brain, and many others. These characters are completely independent from Logan, Patton, Roman and Virgil, and each group of characters follows their own continuity and has their own personality traits and tropes. More so, Thomas has also announced that there will be no kind of interaction between each universe for the time being, so, even though it has been repeatedly requested by many Fanders, Sleep will not appear on Sanders Sides until further notice.
- Author Phobia: Thomas has arachnophobia, that is, a huge fear of spiders. Spiders in turn are a mortal enemy for both the Dad Guy and Patton.
- Breakthrough Hit: Thomas' first viral Vine was this one, one of the Stewie Griffin Vines, where he delivered this line, in Stewie's voice, in a real life drive-thru, to a shocked-laughing attendant:Stewie: Yes, I'm gonna have ice cream, but no sprinkles! For every sprinkle I find, I shall kill you!
- Creator Breakdown: In 2017, Thomas went through a painful romantic break-up. To help him release his feelings and ease his pain, Joan, inspired on Thomas' story, composed for him "The Things We Used to Share", and together they later wrote the two-part episode "Moving On" from "Sanders Sides" where the Sides try to help Thomas find a way to move on after a break-up.
- Dawson Casting: When Thomas started doing his High School Vines back in 2013, he was already 24 years old, however he looked so young that everybody assumed he was really a teenager, and some still think it nowadays.note When he grew too old to convincingly play a teenager, and also to avoid any misconstructions, he phased out the high school student character in 2017, except for a remake of an old Vine he did in 2018, and from then on, in the High School Shorts, he would exclusively play the Teacher Guy.note
- Fan Community Nicknames: Fans of Thomas are called "Fanders." In the early days of his Vine career, some of them called themselves "Sanderlings" or "Foster Children", for Thomas' first Twitter username, Foster Dawg, but "Fanders" quickly became the preferred denomination.
- After Thomas stated in a livestream that he considers his fans to be a sort of family, this mutated into Famders, although this name didn't stick for long.
- Fun T-Shirt: He has several t-shirts available. One of them (now discontinued and permanently out of stock) had one of his Misleading Compliments split to the front ("They'll never find your body...") and back ("...more beautiful than I do!").
- Irony as She Is Cast: Thomas is an accomplished singer, but he can sing not so good, or plainly horribly bad if required by the script.
- In a short, Dominic and Kenny discover that Thomas has been learning to play ukulele, and they ask him to play and sing something for them, "whatever is in [his] heart." Thomas immediately starts singing with a horrible, out of tune, screaming, RIP-Headphone-Users-like voice this single verse:Thomas: I HATE BEING PUT ON THE SPOT! WHY ARE YOU MAKING ME DO THIS!?
- Unless he feels motivated by something related with Crofter's, Logan hates singing, and sings out of tune when he tries, prefering to rap instead. Joan commented in a blooper that Thomas' out-of-tune voice as Logan "sounds like a robot".
- In a short, Dominic and Kenny discover that Thomas has been learning to play ukulele, and they ask him to play and sing something for them, "whatever is in [his] heart." Thomas immediately starts singing with a horrible, out of tune, screaming, RIP-Headphone-Users-like voice this single verse:
- Missing Episodes: Thomas YouTube channel was started back in 2009. Between that year and 2014, he published several YouTube videos that later, between 2014 and 2015, were subsequently hidden or deleted for one reason or another. There are references on his Twitter account, on tweets dating back to 2013, that he had published lots of covers of songs by that date, citing titles like "Wonderwall", among others. Up to 2019, only three of these covers had survived: the "Cup Song", "A Dream is a Wish Your Heart Makes" and "Snow in Venice". The rest were hidden or deleted. Some more recent YouTube vlogs have also been deleted or hidden out of view, among them the "Halloween Thriller Vlog" from 2016 (previously known as "Halloween Vlog Gone Wrong"), the first installment of the "Prank Phone Challenge" series he did with Leo the Giant, and the prank he did on ComicCon 2015 where he was disguised as an old man who wouldn't stop farting. This last one is still available only on the Internet Archive. On 2019, one of the hidden videos, an a-capella cover of "Falling" by Alicia Keys he did back in 2011 was made public again after Thomas attended a special concert by Alicia Keys during a YouTube convention for creators.
- Playing Against Type: Thomas became huge in Vine playing nice, funny and lighthearted characters. Then, on the peak of his Vine popularity, he was cast as the psychopath serial killer J.D. from "Heathers: The Musical", which, as he said, he saw as an opportunity to expand his boundaries and grow as an actor, but which forced him to publish a vlog where, apart from promoting his new show, he gave a serious warning to his habitual viewers to seek for parental permission if they were underage before trying to see him in this show, so far away from his usual stuff.
