The director of Udon, Katsuyuki Motohiro , was born in Kagawa, the place where this movie is set.
The song sung by the hero and his friend is called "Banzai". This was (and still is) a popular song from 1990's Japan. The song was actually performed originally by the actor who is the hero's friend.
In an early scene a bear appears in the movie. There are bears in Shikoku island of Japan but their numbers are quite low.
Tortoise Matsumoto is a rock artist with a group called "Ulfuls". The song performed after the udon festival by the hero and his friend (played by Matsumoto)is actually a popular Ulfuls song called "Banzai".
This movie is set in Kagawa prefecture in Japan. It is the smallest prefecture and somewhat rural. It is famous for udon noodles.