O'Horgan directed and composed the score for the screen adaptation of Futz with Frederic Forrest, Sally Kirkland, and Jennifer O'Neill, and directed the film version of Eugène Ionesco's Rhinoceros starring Zero Mostel, Gene Wilder, and Karen Black (and which featured a score by Hair composer Galt MacDermot).
The screen adaptation of Futz was scored by O'Horgan in collaboration with Frederic Forrest, Sally Kirkland, and Jennifer O'Neill. Meanwhile, the film version of Eugène Ionesco's Rhinoceros, starring Zero Mostel, Gene Wilder, and Karen Black, featured a musical composition by Galt MacDermot.