Director Josh Boone is a major X-Men fan and owns a large amount of their comics.
This film features four members of the original New Mutants group (Cannonball, Mirage, Sunspot, Wolfsbane), with Magik being a member from the second roster.
Blu Hunt is Native American and Henry Zaga is Brazilian, just like their respective characters Danielle Moonstar and Roberto da Costa. However, British actors Charlie Heaton and Maisie Williams play the American Sam Guthrie and the Scottish Rahne Sinclair, and the Argentinian-English American actress Anya Taylor-Joy plays the Russian Illyana Rasputin.
True O'Brien auditioned for the role of Danielle Moonstar.
The filmmakers described the film as "a haunted-house movie with a bunch of hormonal teenagers," and cite the works of horror storyteller Stephen King and teen drama filmmaker John Hughes as an influence.
Illyana carries a dragon toy. This is a homage to Lockheed, a pet dragon owned by the X-Men (in the comics he was owned by Kitty Pryde/Shadowcat, in this film he is owned by Magik).
The Demon Bear is the first X-Men villain to be an animal being.
Nat Wolff was considered for the role of Cannonball.
Magneto is rumored to be involved in the film. Magneto was a mentor to the New Mutants in the comics.
Maisie Williams is the fifth "Game of Thrones" actor to work on an X-Men film, after Peter Dinklage (Tyrion Lannister and Bolivar Trask in X-Men: Days of Future Past (2014), Ed Skrein (Daario Naharis and Ajax in Deadpool (2016)), Sophie Turner (Sansa Stark and Jean Grey in X-Men: Apocalypse (2016)) and Richard E. Grant (Izembaro and Dr. Zander Rice in Logan (2017)).
Illyana Rasputin/Magik is Russian (just like her brother Peter/Colossus) Wolfsbane is Scottish Mirage is Native American Sunspot is Hispanic Cannonball is from Kentucky
Caio Paduan was considered for the role of Sunspot.
Josh Wiggins auditioned for Cannonball.
This will be the 4th appearance of James McAvoy as Charles Xavier and his 2nd movie with co-star Anya Taylor-Joy.
The lettering for the promotional logo reflects the eclectic artistic style of Bill Sienkiewicz, who drew the New Mutants comic in the 1980s.