On May 19, 2012, a bronze statue of the Japanese dog Hachiko was unveiled at the train depot at Woonsocket Depot Square where the film was shot. It is an exact replica of the bronze statue of Hachiko which resides in front of Shibuya Station in Japan.
According to the movie's closing cards the real Hachiko died in March 1934. The earlier movie, Hachiko Monogatari, and other sources state that he died in March 1935 (9 years and 9 months after Professor Ueno's death).
Parker uses Netscape 3.0 on Mac OS (classic) to browse the Internet on October 26, 1996, the date of the sixth game of the 1996 World Series. This is historically correct as the browser was released on August 19, 1996. The websites that he visits appear to be large static images, which contain the whole page pre-rendered separately.
In Chapter 6 of the book "Animal Stars: Behind the Scenes with Your Favorite Animal Actors", trainer Mark Harden describes how he and his team trained the three Akitas - Leyla, Chico and Forrest, who played the role of Hachi in the movie. Harden adopted Chico after the movie was completed.