Based on a novel entitled 'A Case of Need', published in 1968 and credited to Jeffrey Hudson. Decades later, Hudson was revealed to be a pseudonym for Michael Crichton.
Blake Edwards disowned the final film due to constant studio interference. He originally planned to leave the project during production but after MGM threatened to destroy his career, he finished filming and quit the day production ended.
When Dr. Carey drives erratically to intimidate his passenger into telling him what she knows about the murder, her passenger side window alternates between completely open and completely closed.
When Carey jumps the bridge, the front hubcaps can be seen flying off the front wheels of his station wagon. The hubcaps then reappear back on the car.