During the course of the movie, the possessed 12-year-old girl's face becomes increasingly pale and streaked with bloody lacerations, and her eyes begin to redden and sometimes roll back (in a later scene we realize that her whole body has been affected); her voice becomes very low and scratchy, she develops a large lump in her throat and makes various, very eerie and frequently animalistic sounds. Despite the age of the film, she still looks very frightening.
During one scene (only in the restored, director's cut for the film's 2000 re-release) she goes down a flight of stairs bent over backwards -- she looks like a giant spider, spitting blood. VERY disturbing scene.
During other scenes she is violently thrown back and forth on her bed; she levitates; her head spins all the way around; she spits green phlegm/vomit at a man (actually pea soup); blood comes out of her mouth; she projectile vomits green goo, projecting it on several bystanders and covering their faces; she urinates in public (we see urine trickle to the floor); and, the words "Help Me" appear on her body from the inside (presumably from the real person trapped within).
During one of the manifestations of the demon, the young girl grabs a man's crotch very violently (he screams in pain), and has to be forcefully lifted of him and restrained. She spends the majority of the second half of the move tied to her bed.
Strange noises and demonic-looking or monstrous faces are evident in a few scenes, and household furnishings become animated: candles flare up, pictures fall off walls, a bed starts to shake vigorously.
A room shakes and walls and doors crack and split, the temperature drops suddenly, and stuff flies around by itself, in one scene, flying toward the mother.
The young girl at one point masturbates very violently with a crucifix, resulting in self-mutilation (sound effects that would usually be reserved for a blade puncturing flesh are dubbed in) a great deal of blood about the girl's crotch, which splashes onto her clothes, hands and face; her mother's face is later smeared in the blood after the girl shoves her mother's face down into her crotch, growling, "lick me!" She then throws her mother across the room onto a wooden floor, and the woman screams in agony. The possessed girl, who is facing away from the mother, suddenly turns her head 180 degrees around to face her mother and asks her, "Do you know what she did, your c**ting daughter?" Very graphic and disturbing. The mother's face is badly bruised on one side in the next scene.
The possessed 12-year-old girl attacks several people: she hits or slaps several, grabs a man by the crotch and pushes him down; a man grabs her, throws her down, punches her several times and tries to choke her.
A man commits suicide by jumping out of a window and tumbling down several flights of steps.
A person gets an injection, blood is drawn for testing and a catheter is inserted on a person's neck (some blood is evident).
A bloody gash appears on the girl's leg when she's sprinkled with holy water.
Several dogs are shown fighting each other.
We are told that a man died when he was pushed down some steps and that his head was turned backwards.
We see a dead body, and a pool of blood next to the body.
One of the priest starts brutally beating the processed girl.