He initiated the development of three cameras for the IMAX format -- the high-speed (slow-motion) camera, the industry's first lightweight camera, and the "all-weather" camera used during filming on Mount Everest.
In August 2005, MacGillivray was producing a documentary which examined the potential effects of a hurricane hitting New Orleans. By the end of the month, Hurricane Katrina struck Louisiana and MacGillivray filmed the events rather than creating a hurricane simulation as originally planned.
MacGillivray with partner Jim Freeman founded MacGillivray Freeman Films. Freeman was killed in a Sierra Nevada helicopter crash in 1976. MacGillivray keeps his partner's name in memory as a memorial.