गूफ़

Several times throughout the What It Sounds Like sequence, Rumi's right earring disappears.

Early in the song of "What It Sounds Like", when Rumi sang the line "I broke into a million pieces", Rumi's hoop earrings on her left ear and wing ear cuff on her right ear are missing. The missing ear accessories are back as Rumi sang the line "In the broken glass". Both ear accessories disappear again when Rumi summons her sword on the demon swarm attack and once more when the girls reunited to embrace each other in a hug.

During the Saja Boys final performance of "Your Idol" Mira and Zoey are shown in quick closeups were they are portrayed as being on the wrong side of the stage compared to the shots showing them entering, walking hypnotized through, and later emerging from the audience stands.

During her bathhouse fight with Jinu, while Rumi is pinning him down, the tear on her sleeve isn't visible. In spite of being significant enough in subsequent shots to suggest partial visibility.

Near the ending of the song sequence of "Free", Rumi is shown with demon patterns on her hands when she and Jinu held each other's hands. Rumi's demon patterns should not have reached this point yet until her demon side gets exposed on the Idol Awards stage. This error was also seen again in a flashback scene later in the movie when Jinu is about to have his reward granted by Gwi-ma.

When Bobby first calls the girls while they are on the plane, the phone screen shows a call that's already three seconds in starting simultaneously with the ringtone.