Jennifer Aniston drew inspiration from her friend and colleague Stacy Courtney. Courtney worked as a stunt-woman until she was involved in a serious accident with her legs, which immediately put a hold on her career. She lived with chronic pain for years, and went on to receive 23 surgeries and became addicted to oxycontin. However, she didn't give up and later resurrected her career. She worked as a stunt coordinator on this film.
Jennifer Aniston does not wear any makeup in the film at all, except for the kind used to create her fake scarring and when Roy (Sam Worthington) comes to lunch in her house.
The screenplay for this film was featured in the 2013 Blacklist; a list of the "most liked" unmade scripts of the year.
When Jennifer Aniston is at the pain specialist's office to get more pain medication, she mentions that her primary care doctor is a Dr. Shipman. A real Dr. Shipman was convicted in 2000 for his part in the murders of 250+ people. Many of them were his patients using overdoses of painkillers. He committed suicide in prison in 2004.
Jennifer Aniston admitted in an interview, that she was not the first choice for the role and that she was only considered for the part, since another famous actress declined it upon reading the script. Aniston has not specified which actress originally was approached.