Bingowings said:

For starters the premise is slightly hamstrung by the inability of the film makers to secure rights to the genuine horror film monsters.

If this was properly negotiated it could have been the Roger Rabbit of horror films.

I couldn't disagree more. It would've taken me completely out of the film if it were full of recognizable horror monsters. I liked the idea that the horror monsters seen in actual Hollywood films are based, subconsciously, on these elemental archetypal creatures seen below the cabin. In a way, that's what happens in real horror films, they use tropes and monsters that have been part of folklore for hundreds or thousands of years.

Do you know for certain that Whedon and Goddard were ever interested in securing the rights to genuine horror monsters, or is this just an assumption?