Mona accuses Alex of plagiarizing and stealing the melody of her husband's song and incorporating it into Alex's new tune, "Pearls and Jade." Mona throws her drink at Alex, hitting him in the face and left shoulder. When the camera angle cuts to a closeup shot, both shoulders are wet. A switch back to the wide angle shot shows Alex back to one wet shoulder. Then, the next closeup shows two wet shoulders again.
At the very end when Perry, Paul, and Della were talking, the papers to Della's right are neat and in the folder, but when the camera scans her again, the papers are all messy.
The title refers to a "domino," which is a mask that covers only the area around the eyes and the space between. But all of the Halloween masks worn by the children, including the mask worn by the killer, are full-facial masks, not domino masks.