Instead of the usual "Special Guest Villain", Van Williams as the Green Hornet and Bruce Lee as Kato are billed as "Visiting Hero" and "Assistant Visiting Hero", respectively.
Pink Chip Stamps is a sly nod to Blue Chip Stamps, which were a popular brand of trading stamps at the time.
This was not the first appearance of The Green Hornett and Kato on Batman. They had previously appeared in episode 2 of the second season during a window cameo as Batman and Robin climbed a wall. They all seemed to be aware of each other which was not the case during episide 51 here. Also to make things more confusing, there are two episodes that end on a joke where Bruce Wayne sits down and says he is about the watch The Green Hornet on TV.
Such a live action crossover/team up between two heroes was quite rare, and largely unprecedented for the time. In the past Batman had appeared on the Superman radio series, and there would be numerous super hero teamings in animated projects over the years, but such high profile live action team ups did not become common until the 2010's.
Star Trek, which aired at the same time as this series, also had an episode with this same title. Also, this episode guest-stars Roger C. Carmel, who plays the reoccurring Star Trek character Harry Mudd and Angelique Pettyjohn who plays Shahna on the Star Trek episode 'The Gamesters of Triskelion'.