The movie was filmed during the Christmas season in New York City, exactly the period in which the story takes place. The producers have said that, being on an indie film budget, the timing allowed them to save money by not having to build holiday sets.
Caren Lissner, the author of the novel, has a cameo in the Central Park scene at the end, sitting on a bench reading. She has three books in her lap: the British and Spanish versions of Carrie Pilby, and Be More Chill by Ned Vizzini.
The movie was filmed in only 20 days, mid-December of 2015 to mid-January of 2016.
Caren Lissner who wrote the novel has said that she named the character of Cy after lyricist Cy Coleman.
The ringtone of Carrie's phone is "In the Hall of the Mountain King" by Edvard Grieg.
"Morning Mood", another piece from the same composition ("Peer Gynt, Op. 23") is also featured in the movie.