Avatar: The Last Airbender references: While traveling through the Midnight Desert, Callum, voiced by Jack De Sena, says "This looks familiar.... boomerang?" This is a tribute to the boomerang-wielding character Sokka from Avatar: The Last Airbender, who was also voiced by Jack De Sena. There is also a reference in the first episode, when Claudia is reading a book while walking across a courtyard. The book is called 'Love Amongst the Dragons', the same name as the play mentioned by Zuko in the season three episode The Ember Island Players(2008).
The dark magic spells are actually English phrases spoken backwards. For example, when Claudia casts the spell to find Rayla, she chants "Fle wodahsnoom eht kees", which reads backwards as "Seek the Moonshadow Elf".
Lord of the Rings reference: In a discussion on taking the Dragon Prince to Xadia, Callum says "One does not simply walk into Xadia", paraphrasing Boromir's famous line "One does not simply walk into Mordor".
The character designs for both Ezran and Claudia have the exact same color schemes as their fathers, respectively King Harrow (red and gold) and Lord Viren (black, gray, gold, and purple). Callum's character design also includes red and gold, but they are partly covered by a blue jacket, emphasizing his peculiar status in the family (half-brother of Ezran, stepson of Harrow). Soren also has a similar color scheme to Viren and Claudia but with a lack of purple; note that in the show the color purple is associated with magic and Soren, unlike his father and sister, isn't a mage.
The first scene Aaron Ehasz wrote was a mage (who would become Viren) teaching his child about primal versus dark magic. The child's personality was divided as the series was written further between two characters, who became his children Claudia and Soren.