On the DVD commentary, Michael Shannon and the director, Jeff Nichols, both clarify that the daughter was not supposed to have been born deaf but had become deaf a few years before the events of the movie due to an illness like meningitis.
In the DVD commentary, Michael Shannon points out that the pills that Curtis takes are actually mint-flavored Tic Tacs.
The insurance agency in this film that assists in getting the daughter's implant is a real agency with several locations in Ohio, where the movie was filmed.