Director Mamoru Oshii mentioned that the scene recreating the original Godzilla (1954) film had to be done by entirely by memory since the film wasn't available on home video yet to use as a reference.
In Ataru's harem dream, Benten and Kurama appear among the dancing girls. Also, one of the girls seen embracing Ataru is Kyoko Otonashi from Maison Ikkoku (1986).
The movie is based around an old Japanese folk story named "Urashima Taro". This tale shares similarities to "Rip Van Winkle" and "Pandora's Box", and is one of the stories Japanese children learn.
Members of the animation staff appear briefly during the "Day before the festival" scene. They are riding a cart marked "STAFF".
Tomobiki High School's broken clock tower was damaged in the previous movie, Urusei Yatsura: Only You (1983), courtesy of one of Lum's high-voltage tantrums.