Onibaba's literal meaning is demon hag or old devil woman.
The demon mask used in the movie inspired William Friedkin to use a similar design for the makeup in subliminal shots of a white-faced demon in The Exorcist (1973).
The tall grass seen throughout the film is miscanthus or Japanese silver grass. In Japan it is known as susuki.
One of Willem Dafoe's favorite films. He briefly owned the rights to the film and was planning on making a remake but eventually abandoned the idea. It was too difficult to rework the story into a new setting for a contemporary audience while remaining respectful to the source material.
The story was inspired by a Shin Buddhist parable known by two titles: 'yome-odoshi-no men' (bride-scaring mask) or 'niku-zuki-no-men' (mask with flesh attached).