20 Things You Didn't Know About Eyes Wide Shut
5. The Significance Of The Mask On The Pillow
In the closing act of the movie, Bill, to his horror, finds his Venetian mask has been placed upon his pillow, next to his sleeping wife, Alice.
Who placed it there and why? The obvious answer is Alice, she put it there to show Bill that she knew where he'd been but can it be that simple?
It's possible that it was placed there by the perpetrators of the orgy as a warning but why then didn't Alice mention it? There third option could possibly be that the presence of the mask is entirely in Bill's head - a symbol of his guilty conscience.
The final possibility is that Alice was involved in the orgy; she does describe a nightmare in which she is with multiple men, although this would inconsistently alter the concurrency with the source material.