Quicksand Fans

Send Help stars Rachel McAdams and Dylan O'Brien in a thriller where two co-workers get stranded on a desert island. The movie trailer is a cross between Cast Away and Misery. In one of the brief frames (2:09), there looks to be a muddy female hand reaching up. It can't be seen in the trailer where the arm is or who it belongs to. The hand has nail polish and from what I have seen Rachel McAdams doesn't have any nail polish on in the movie.

Here are some of the captured stills from the trailer.

I think you may be reaching here. I see a black woman's hand in a claw position, perhaps representing something evil. We can still hope though.