Visible crew/equipment: When the camera is pulling back really fast being chased by the people in Africa, its shadows can be seen multiple times on the characters and the walls.
Exorcist II: The Heretic (1977)
1 visible crew/equipment mistake
Directed by: John Boorman
Starring: Max von Sydow, Richard Burton, Louise Fletcher, Linda Blair
Factual error: Father Lamont tears out the Regan doppelganger's heart from where her stomach should be. Even allowing that she's a manifestation of a demon and may not conform to human anatomy, it isn't plausible that Lamont would know to grab for her heart through her abdomen.
Father Lamont: I've flown this route before. It was on the wings of a demon.
Trivia: This sequel was so notoriously hated, supposedly during the first sneak-preview screening, studio executives in the audience were chased out of the theater by a group of angry filmgoers. William Friedkin, director of the original film but not this sequel, also saw a few minutes of the movie while visiting the Technicolor labs and described the experience by exclaiming, "I see some guy on the back of a bumblebee or some fucking thing... it was unreal! Ugh! And I left!"