Legend has it that long ago, the most infamous villains were imprisoned on the Isle of the Lost, cut off from the rest of the world as a punishment for their misdeeds. In this dark and dreary place, the likes of Maleficent, Jafar, Cruella De Vil and the Evil Queen reside and evil reigns supreme. Mal, Evie, Jay, and Carlos are their descendants, the teenage sons and daughters of the Isle’s most villainous characters, and they are coming of age on the Isle of the Lost.
- King Beast has a Council made of the sidekicks of other heroes such as the 7 Dwarves, Cinderella's mice friends, Pongo and Perdita, Ariel's sisters and Flounder, Flora, Fauna and Merryweather and the Genie.
- The locations from The Hunchback of Notre Dame, Tarzan, the Jungle Book, Pocahontas and The Emperor's New Groove are suggested to be part of Auradon. Theoretically, these locations could be in the west of the USA, which is never given any kind of description in the book.
- It's likely there's some kind of makeshift gas station on the Isle of the Lost, as Cruella is mentioned to still possess and drive her red car.
- Three different shows are mentioned to have appeared on Carlos's TV when he briefly pokes a hole in the barrier. From the descriptions, it's likely the shows were Dog with a Blog, Liv and Maddie, and Mighty Med.
- Cruella is never mentioned to have some sort of way to get income, suggesting she either mooches of Horace and Jasper, or has created a new version of her De Vil Fashion company on the isle, and takes profit as owner.
- London is mentioned by Carlos, which would have served as the original home of his mother and Professor Ratigan.
- Hell Hall is suggested to have already existed on the island, or was rebuilt per Cruella's request.
- The food, make-up and clothing sold on the island are leftovers from the United States of Auradon. The inhabitants prefer spoiled and unhealthy food, believing proper food would make them soft.
- Rusty coins pass as currency on the Isle of the Lost.
- The powerful wizard Yen Sid was sent to the island by King Beast to teach the villains how to adapt to using science instead of magic, being one of the teachers in Dragon Hall.
- The Forbidden Fortress is in the barrier, since the Dragon's Eye was too dangerous to be kept in Auradon.
- Iago appears to be losing the ability to speak fluently, due to the years on the Isle of the Lost. (At one point, he insults Jafar in normal speech; other wise, he just repeats things.)
- Diablo comes back to life, but is nowhere to be seen in the film. Additionally, he is not mentioned in the sequel novel. (Plot hole)
- In overview of the four lives on the Isle of the Lost, Mal and Evie are actually treated much better than Carlos and Jay. Mal is usually left to her own devices as Maleficent couldn't care less, while Evie at least treated like a princess by Evil Queen; Carlos is used as a slave by Cruella, while Jay is never able to impress Jafar, who dreams of finding a "big score" to leave the isle.
- When Mal was considering an evil scheme for her class assignment, she never considered the worst one - taking a life; this could be a sign of her inner goodness.
- Other villains mentioned or hinted at are Captain Hook, Ursula, Dr. Facilier, Mother Gothel, Lady Tremaine and her daughters, Clayton, Madam Mim, Ratcliffe, Gaston, Professor Ratigan and Judge Frollo.
- The video "Unlocking Secrets" confirms that the book is in fact connected to the film.