Continuity mistake: In the scene in the orgy house, when women start walking to other people one by one: the woman which will approach Tom Cruise at one point has no neighbours in the circle (because two women at her sides already left), but later she is kneeling next to another woman with big mask, who was three 'seats' to her left earlier. (01:13:40 - 01:14:10)
Continuity mistake: Cruised is mobbed by some guys and stumbles towards the blue car's trunk. When the angle changes he is half a metre behind, next to the passenger's window.
Continuity mistake: When Tom Cruise is going to return the costume, he walks up the stairs to the apartment building and enters when a person leaving the building opens the door. The next shot is then him walking into the Rainbow store, which is next to the building.
Continuity mistake: When the movie starts, Cruise and Kidman greet the nanny, who puts her around the girl. When the angle changes, her arm is away and she is surrounding the girl again.
Chosen answer: I think someone from the freaky orgy broke in and put the mask on the pillow to warn Cruise's character to keep his mouth shut. That's why Cruise's character is so upset-they got into his home and his safe.
I always assumed that she was a member of the orgy party. She was letting him know that she was there.
No, she wasn't.