Emilia Jones spent nine months learning American Sign Language, having singing lessons, and learning how to operate a fishing trawler.
Troy Kotsur is the first deaf male actor to win an Oscar. His wife in the movie, played by Marlee Matlin, was the first deaf female actress to win an Oscar in the 59th Academy Awards 35 years ago (March 30, 1987) for Les enfants du silence (1986).
The on-set interpreters were all CODAs (Children of Deaf Adults).
Because the fishing scenes involved real fishing, the cast and crew had to abide by local fishing rules. One day, they had to bring an observer with them and they had to move one of the crew members from the boat set since they could only have a maximum of 10 people on the boat.
According to Troy Kotsur, the film initially was rated R "for language," as displayed in the subtitles during the deaf character's dialogue in some scenes, but after several "back-and-forths" and fights with the MPAA, it ultimately was reduced to PG-13 months before its official release.