Barbara Hershey said, "I resent being put in the position of defending the film. We worked really hard not to make it exploitative. Rape is one of the ugliest, if not the ugliest thing, that can happen to someone. It's murder of a sort. I have no answer for those who are offended. They're right, but I don't think our intention was to exploit the subject, or the result. Truly, I don't. I think we did well with it." When Hershey was interviewed for the Scream Factory Blu-ray of The Entity in 2018, she had nothing but kind words to say about director Sidney J. Furie, even saying that going to work on it was fun and stress-free because he was at the helm, making her feel comfortable, safe, and protected at every turn. She also described it as one of the best creative experiences of her career.
The film's closing epilogue states, "The film you have just seen is a fictionalized account of a true incident which took place in Los Angeles, California, in October 1976. It is considered by psychic researchers to be one of the most extraordinary cases in the history of parapsychology. The real Carla Moran is today living in Texas with her children. The attacks, though decreased in both frequency and intensity...continue." According to an update by the Conneticut Paranormal Research Society web-page article titled "The Carla Moran Story, the Entity,""The woman [Carla Moran] moved five times, but the attacking entity followed her. She eventually moved further away. As she moved, the phenomena diminished, and after about two years, the attacks stopped altogether."
The real-life Carla Moran's teenage son described a particularly vicious attack in which Carla was thrown by the malevolent force and hit her head. He tried to intervene, but he was also thrown, breaking his arm. In the filming of the movie, the actor playing the son broke his arm in that scene, and the curtains tore from top to bottom without explanation.
This movie is based on the real life attack of a Californian woman named Doris Bither. According to Bither, she was constantly raped by the spirits of three men. Two would hold her down while the third raped her.