Shortly after the film's release, producer William Castle began to receive hundreds of pieces of hate mail. "Bastard. Believer of Witchcraft. Worshipper at the Shrine of Satanism," one letter read. "My prediction is you will slowly rot during a long and painful illness which you have brought upon yourself." Around the same time, Castle began experiencing excruciating pains in his groin. He collapsed in October of that year, four months after the release of Rosemary's Baby. He'd had a blockage in his urinary tract.
It's widely known that the film used the exteriors of the Dakota Apartments in NYC to shoot certain scenes. The very same building was the scene of John Lennon's murder in 1980. Lennon had actually crossed paths with Farrow in the Spring of 1968. They met at the Maharishi Mahesh Yogi's ashram in India.