"X" crew members would frequently accidentally show up to the much larger set of "Big Little Lies", which was filming at the same time nearby in Monterey.
Director/co-writer Scott J. Ramsey, producer/co-writer Hannah Katherine Jost, producer/co-composer Kevin De Nicolo, and lead actress Hope Raymond were all members of the Epsilon Chapter of the co-ed cinema fraternity Delta Kappa Alpha at San Francisco State University, their alma mater.
Each of the songs on the film's original soundtrack are named after playing cards.
The original story idea for "X" featured Christian's character as a male. She was changed to female before the first draft of the script was written, but her original name was kept.
"Pendragon", the password to get into the ball, is a reference to Uther Pendragon, King Arthur's father in "The Once and Future King".