Wow...I am think I just stumbled on something huge. Two scenes that may show that Kidman was at the ritual.

There is a scene earlier in the movie where she drops her black dress around her feet. She is nude, except for black heels, facing the red curtains and her face is not seen.

Flash forward to the ritual....

Women are around the men in red in black cloaks. They drop the black cloaks to their feet. They are basically nude, in black heels and their faces are not seen because they are masked. One of the women has long, curly, red/auburn hair. She also has a body similar to Kidman's and heels practically identical to the early scene.