Mothra stars in the movie because a poll showed that she was the most popular monster among women, who made up the bulk of movie-going audiences. The lighter tone, the family-oriented romance story, and child main character were all put into the movie to appeal more to a crowd of women and children. These factors contributed to the film's box office success, becoming the most successful Heisei film and bring in profits not seen since the the golden age of the 1960s.
During a trip to Japan, director Tim Burton was on the film-set during the first day of special effects filming.
This film's origin went back to 1990 with the concept Mothra Vs. Bagan. The film would include battles all across Asia in places like Shanghai and Bangkok. However, when Gojira tai Biorante (1989) did not turn out to be the hit Toho wanted, they felt that it was because of an unfamiliar monster was used and this project was put on hold to give Godzilla another shot with Gojira tai Kingu Gidora (1991).
In the movie, the characters don't react with much of a surprise to the appearance of Mothra, her fairies and Battra. When asked why this is, director Takao Okawara just said "It's a monster movie, so of course it has monsters in it."