The Beast Within pays tribute to Lovecraft’s The Case of Charles Dexter Ward novella by using the names of “Charles Dexter Ward” and his alter ego “Joseph Curwin”.
There’s a novel by the same name from Edward Levy originally published by Arbor House Publishing in 1981.
It involves a possession process and a final transformation of the main character in an unidentifiable monster a sort of rubber alien with a cicada-like head that can fly.
There’s a sequence during the possession process in witch Michael is exposed to meat blood. An old man invited Michael to come over for dinner and for unclear reason plays with the meat using his hands. Michael overreacts and attacks the old man.
Somewhere, there’s a put on bra scene repeated twice.
There’s a pursuit of the creature against the mayor.
There’s an obscure tale told by the mayor. It goes approximately like this : a man violate the wife of another man. In order to revenge himself the late man close down the violator and nourish him with corpses. One day, he flew and violate a women. That’s the first scene of the film. The child is Michael, the main character.