Frances McDormand, Sam Rockwell and writer-director Martin McDonagh have all collected Golden Globes for their work on Three Billboards Outside Ebbing, Missouri, but if it were not for film editor John Gregory, himself recently nominated for an American Cinema Editors Eddie award, that might not have been the case.

For as Gregory and McDonagh cut the film, they realized that McDormand's Mildred, who uses billboards to urge police to solve the case of her daughter's rape and murder, could come across as an off-putting, even alienating character. And so, in a key decision, they decided to move a flashback of Mildred's final conversation with her daughter, which ends in an ugly argument, to an earlier point in the story. In so doing, they quickly realized that their decision changed the character.

Gregory explains that in the original script, the flashback occurred deeper into the film, but the filmmakers became concerned that "by leaving it so late, you're going to lose sympathy with this woman." When her billboards burn down, Mildred sets fire to the police station, "which is really very neurotic," he admits. But by setting the flashback earlier in the film, "You know that it's not really about the burning of the billboards; it's about her trying to come to terms with the last conversation with her daughter. If you know her story a lot earlier, you are more sympathetic with Mildred no matter what she does."

Similarly, careful editing helped shape Rockwell's character of Dixon, a racist police officer. "On the surface of it, he's a really nasty guy," says Gregory. "His change, to the point where you do kind of like him in the end, is a hell of an arc. We had to play that very carefully." But by selecting the right takes, especially Rockwell's reaction shots, the filmmakers were able to show that Dixon also is a "vulnerable young boy. It's just a look in his face and his eyes."

This story first appeared in the Jan. 17 issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.