Van Williams became good friends with Bruce Lee and repeatedly negotiated with the show's producers to give Lee more screen time and lines.
This show crossed over with Batman (1966), and it was revealed that Bruce Wayne and Britt Reid were rivals as youngsters, and Britt was a champion marble shooter.
Kato is a Japanese name, as in the 1936 radio show Kato was Japanese. This was changed in 1939 due to world events. Kato briefly became Korean before settling on Filipino for nearly all of the 1940s. By the 1960s, he was regarded as a generic Asian, enabling Chinese-American Bruce Lee to be cast. Kato is also Chinese in Seth Rogen's The Green Hornet (2011) as a tribute to Lee, but most 21st-century comic book versions restore the Japanese origin.
The character of Britt Reid/Green Hornet was created by the same people who created The Lone Ranger, and was said to be the great-nephew of the western hero.
Bruce Lee once said that he was selected for the role of Kato because he was the only Asian actor who could properly pronounce "Britt Reid."