The movie the girls are watching at the beginning is One Cut of the Dead, a Japanese film that features zombies.
The book Miss Marie sets aside before helping the girls - Stem Cells by Gian Paolo Bagnara, Laura Bonsi, and Francesco Alviano - is a real textbook, published by Società Editrice Esculapio on February 12, 2020.
At the beginning of his 'exorcism', Leland quotes the Wicked Witch of the West's line "I'm melting! I'm melting!" from The Wizard of Oz. When Michael Emerson's character was introduced on Lost, the pseudonym he used was Henry Gale, which is the name of Dorothy's uncle in that same film.