Trivia / Three Billboards Outside Ebbing, Missouri

• Actor-Inspired Element: When researching what accent he would use for Dixon, Sam Rockwell became acquainted with a chief of police from Springfield, Missouri (who had been featured on Cops). The man liked to use the word 'clank' referring to jail, and Sam requested Dixon say it as well.
• Billing Displacement: The posters have Woody Harrelson over Sam Rockwell despite the latter being the Deuteragonist. This is almost certainly because of two reasons. The first is that Harrelson’s a bigger name than Rockwell, and the second is they didn’t want to spoil that Harrelson’s character suffers an early death while Rockwell’s seemingly less important role only goes on to gain prominence after that.
• California Doubling: The small town of Sylva, North Carolina stands in for the titular fictional town.
• Dawson Casting: 19-year-old Penelope is played by Samara Weaving, who was 25 during filming.
• Dear Negative Reader: Martin McDonagh angrily lashed out at everyone saying the movie was too sympathetic to racist cop Dixon, saying they wanted a "movie for six-year olds."
• Defictionalization:
  • Senator Marco Rubio was attacked by three billboards designed after the film's after the following year's school massacre in Parkland, Florida.
  • Activists protesting the lack of action after the Grenfell fire drove a van with three billboards around central London .
• Dyeing for Your Art: Sam Rockwell gained weight for the role. He did wear some padding to make Dixon look chubbier.
• Fake American: Samara Weaving is Australian but plays a Missouri native.
• Playing Against Type: Sam Rockwell usually plays wimps, but here he plays a slack-jawed bully with a badge. Interestingly, the part was written specifically for him (as Mildred was written for Frances McDormand).
• Production Posse: Martin McDonagh had directed Sam Rockwell, Woody Harrelson, Abbie Cornish, and Željko Ivanek in Seven Psychopaths, with Ivanek also appearing in In Bruges. Sandy Martin appeared in Seven Psychopaths too, though her scenes were cut. Also subverted in that this is his first film not to star Colin Farrell.
• Uncredited Role: Nick Searcy as Pastor Montgomery.
• What Could Have Been: Frances McDormand was initially reluctant to take the role of Mildred, fearing she was too old at fifty-eight for it. After much debating back and forth, her husband convinced her to take it. She was Martin McDonagh's first and only choice for the role.