Tom Laughlin had no martial arts training before he started training for the movie. He studied under a master teacher for six months before filming started.
Initially a dud at the box office, Tom Laughlin set up further distribution for a re-release in 1973. This time it was an enormous hit.
Just before shooting on the picture began, several cast members tried to convince Tom Laughlin to not wear his black hat with the Indian headband, saying they thought it looked silly, Laughlin fought back, wore the hat anyway and, of course, it became an iconic trademark of the Billy Jack character.
The film eventually became a huge hit, grossing $32.5 million in the US on a budget of $800,000. It grossed $98 million worldwide.