About the poster art.
It's basically showing the move that Dux uses to defeat Jackson in Karate Champ.
shareI never saw that jump kick poster before. I only ever saw this poster...
https://movieposters2.com/Bloodsport-1988-movie-poster_1540172.html
... which is the one they used for the original VHS cover in the US.
By the way, that's a lame move in arcade Karate Champ. It only works on the first couple computer opponents, and it only works on a human opponent who doesn't know how to block. Trying it on someone who knows how to play sets yourself up for, e.g., being kicked in the face (righthand joystick up) after they easily block.