This movie is an indirect adaptation of Yasutaka Tsutsui's novel "The Girl Who Leapt Through Time" - the main character's aunt is Yoshiyama Kazuko, the protagonist of the novel.
When Makoto learns through a text message that Kosuke is going to borrow her bike, he enters "7-2-4" while pronouncing "Ma-ko-to" on the cycle lock. Those figures refer to the numbers of the "rank" of those syllables in the Japanese script (Ma=7, Ko=2, To=4).
This movie was released to a small number of theaters in Japan, taking in approximately 300 million yen (US$3 million). The film wasn't advertised as frequently as other animation features from 2006 (such as "Tales from Earthsea"), but word of mouth and glowing reviews generated interest. At Theatre Shinjuku for days in a row, film-goers would fill the theater, some even standing to watch the film. Following this, distribution company Kadokawa Herald Pictures took unprecedented measures to increase the number of theaters showing the film across Japan, and sent the film to several international festivals.
This is the fifth adaptation of Yasutaka Tsutsui's novel "The Girl Who Leapt Through Time", but the first adaptation to be an indirect adaptation.
The background piano music when Makoto leaps through time is from Johann Sebastian Bach's Goldberg Variations (specifically Variation 1).