The film was completed on August 6th, only 12 days before the official release date in Japan.
The inside of the lightbulb seen throughout the movie spells the word "if" in English. The name of the town, Moshimo, is also "if" in Japanese
This is a remake/adaptation of a 1993-1995 Japanese TV series of the same name.
Directed by Akiyuki Shinbo, who's known for directing Puella Magi Madoka Magica (both the series and the movies)
The conference held at the mid July originally should be the announcement conference for the completion of this film, but the animation was not finished by then. The preview screening was pushed back to the early August, about only ten days before the official release date in Japan.