According to director Terence H. Winkless, the original script had Don 'The Dragon' Wilson's character training by running up stairs of a temple. When he arrived in the Philippines to begin shooting no temple could be found. A live volcano was nearby so he changed the script to have the character training by running up a live volcano as it would make an interesting replacement for the temple.
Out of all 9 Bloodfist films, Bloodfist II (1990) is the only sequel that has any connection to this first film as Don 'The Dragon' Wilson plays the same character Jake Raye. All the other sequels (except for the Wilson-less Bloodfist 2050) have Don 'The Dragon' Wilson playing different characters.
Jake Raye: My brother was in a motorcycle accident. He needed a kidney. Actually he was my half brother but I gave him a whole kidney. And you can't fight with one kidney, it's like suicide. So I had to give it up.