All five girls get in the elevator to go to the basement, however while in the elevator Shayna isn't present. Yet she comes out into the lobby as if she was.
When Tess (Melissa Moore) takes a shower, the straps on her panties can be seen, so she obviously isn't totally naked even though she's showering.
Just past 1:16, when the chick says "This one's still alive!" and picks the girl up from the floor, four inches of the boom mic are very clearly visible at the bottom right.