In December 2019, the film was announced to be 15% complete after three-and-a-half years of work. Producer Toshio Suzuki explained that Hayao Miyazaki, in the past, would be able to direct seven to ten minutes of animation per month, and they had scheduled five minutes of animation per month or about one hour per year on the film. However, Miyazaki was directing only about one minute of animation per month.
According to producer Toshio Suzuki, The Boy and the Heron is the most expensive film ever produced in Japan.
Hayao Miyazaki was 83 when he won the Academy Award for Best Animated Feature for this film, making him the oldest person to win the award. The previous record holder was himself, having won for Chihiros Reise ins Zauberland (2001) at 62.
The release of the film was noted for its intentional absence of any promotion, with Ghibli choosing not to release any trailers, images, synopsis or casting details of the film in advance of its Japanese premiere with the exception of a single poster.