- Defictionalization: When the two characters who died in the ring did so (Rikiishi and Joe), both had real-life funerals held for them by fans. That is how popular the manga was.
- Life Imitates Art: Want to know what would've happened if a match like Jose Mendoza versus Joe had happened in real life? Look no further than the very real and infamous Ray Mancini and Deuk Koo Kim match (a good 20 years after the manga had ended), also known as "the reason why no fight lasts 15 rounds anymore.'' While Deuk Koo Kim wasn't punch drunk by any means, he had to go through the process of losing several pounds immediately before the fight to make the weight. The fight lasted 14 brutal rounds. Unlike the manga the fight was stopped in the 14th round after Kim rose unsteadily to his feet by pulling himself up the ropes note after being knocked down. It gave Mancini the victory by TKO. Minutes after the fight was over, Kim collapsed into a coma. He had suffered a major brain injury, and died four days later. What happened to everybody else? Mancini fell into a deep depression afterwards from which -it could be argued- he never trully recovered so if you were wondering how Mendoza would've reacted, there you go. His career and marketeability disintegrated. He eventually came back to the ring, but he was never the same. Kim's mother committed suicide four months after the fight, and the bout's referee, Richard Green, killed himself in July 1983. Needless to say it wasn't pretty, and wouldn't be in the Ashita no Joe manga either.
- The Other Darrin: Some Japanese voice actors were changed for the second anime series, but Nishi in particular goes from sounding cartoonishly deep to sounding rather high-pitched.
- Nishi's voice actors in Latin American Spanish dub done in Los Angeles are quite egregious. For a good chunk of the second series, Nishi sounded like a complete simpleton, but once you get used to his voice, they changed the actor for a more normal and youngish voice in the final episodes. It was quite annoying, actually.
- Playing Against Type: Ryusei Nakao as Carlos. Really.
- What Could Have Been: Ashita no Joe was very seriously considered for an English dub to a American audience. The company that would have taken this endeavor was the little known short lived Almi Pictures (aka Almi Productions). They even created a two minute English dub pitch for the show with dubbed scenes. It's evident that they had already invested in dubbing at least a few of the episodes. The dubbing isn't half bad for an early 80s effort. This can be seen on Youtube and it would have been called Rocky Joe, thus being the source of the popular alternate name. According to the video pitch, it would have been 65 episodes which is far short of the count for both seasons combined (a little less than half), so it's left to the imagination as to what would have been cut and how this would impact the English dub. It is possible that they actually planned to have two 65 episode seasons and that they were just thinking conservatively, one season at a time. Why this dub didn't happen is still a mystery but rumor has it is that the company realized how depressing the ending is and changed their mind.
Trivia / Ashita no Joe