Ellen Burstyn owned the footage of her and Buckminster Fuller together in the car and sailing, that is seen in the film. When the director wanted to cast Burstyn, he had no idea they had met in real life.
Due to limited budgeting, the production couldn't get a teacher to teach Asa Butterfield how to play the bass. Alex Wolff taught him just like in the movie since he's a real-life musician.
Asa shaved his head just for this movie
Although they played brother and sister in the film, in real life, Alex Wolff and Maude Apatow share a month and a half age difference.
According to Maude Apatow, the film was shot in 18 days.