The crux of “Coherence” is the relationship between eight friends, whose dynamic with one another alters and unravels during the fateful night of Miller’s comet. Although the believability of the narrative hinged completely on the chemistry among the group, James Ward Byrkit decided to invite eight friends who did not know one another to his house with “no knowledge of what [they] were doing.”
In the aforementioned interview, the director explained that while he and Alex Manugian had worked on the film’s core idea for over a year, the actors were neither given a brief about their characters nor handed a working script. They just trusted Byrkit enough to show up at his house (where the entire film was shot) and plunge themselves into an experience like no other. This type of unconventional filming approach could have gotten especially tricky, given that the plot features multiple versions of the same character. But somehow, the cast of “Coherence” managed to make it work.
So, how did they go about making the movie? Byrkit explained that every actor was given “a page of notes for what they had to do” every day, which included snippets of character backstory, possible motivations, and vague acting directions. For instance, an actor would be provided with the note “Somehow, get outside tonight,” and they would improvise this while being unaware of what anyone else what told to do. This would produce startling effects, genuine reactions, and naturalistic dialogue, which enhanced the chaos of “Coherence” in remarkable ways. The actors also were unaware of the many power outages that were supposed to be an essential aspect of the alternate reality phenomenon, which made their shared experience seem more authentic.