I'd totally believe that they have sources citing that it is going to be filming in Puerto Rico and Australia... but it's hard to wrap my head around the idea of this thing filming totally in secret like this without anything at all beyond these two little bits of information leaking.
On the off chance this is true, I have to wonder just how tiny this movie actually is. Very small budget, very small in scale, totally under the radar.
My gut inclination is to not believe this. But, hey, I guess stranger things have happened, so I'm not going to totally close the book on it...