Because he hails from England, Danny Murphy was fluent in British Sign Language, which is completely different from American Sign Language. When ASL interpreters first met with Danny, they couldn't understand what he was saying, comparing his signing to a thick Scottish accent. So, Danny learned ASL for the film.
Danny Murphy, who plays Wesley, is deaf in real life, however, his impairment is much more severe than Wesley's, as he is unable to read lips.
Aaron Paul has jokingly referred to this film as "the most light hearted thing I've ever done."
Filming in Sanford, Manitoba, Canada in December 2017 and January 2018
Christopher Cantwell read the script for the film while riding the subway and literally missed his stop because he was so engrossed in the story.