Cynthia Erivo, who stars as Elphaba in the film alongside Ariana Grande ’s Glinda, commented on the surprise appearances during her Women in Hollywood cover interview with ELLE. However, due to the secrecy of their appearances, the details of how it all came together couldn’t be revealed until now.

Chu’s colorful spectacle (★★★ out of four; rated PG; in theaters Friday), adapted from the popular Broadway musical (based on the Gregory Maguire book) and a revelatory prequel to “The Wizard of Oz.” The song-filled character study of the Wicked Witch of the West’s early years ekes out great performances from Cynthia Erivo and Ariana Grande that’ll wow musical theater kids and old-school “Oz” fans alike.