Makoto Shinkai intended to draw the background art himself but with an estimated 1000 cuts needed this would have been impossible for Shinkai to do alone and the film's animation producer, Kiyonori Hiramatsu went to Tokyo Art University to scout for artists. Adding to complications, many of the students were recruited from oil painting classes and had no experience in creating digital backgrounds and many hadn't even used PCs before.
The film was intended to run at 60 minutes but ballooned into 90 in the final cut.
The book Fujisawa is reading on the train during his journey home is Kenji Miyazawa's Haru to Shura (Spring and Asura).
The unmanned aircraft in the movie is a futuristic design of the RQ-/MQ-1 "Predator" unmanned aerial vehicle (UAV).