Q] Why does Guy beat up Cody in the ending?
A] Contrary to popular belief, Guy did not beat down his friend because he was jealous that he got the girl. The actual reason is, however, is that Guy was so shocked that Cody didn't stop when Jessica called his name -the entire point of them going on this quest was to save her, so Cody could at least talk to her afterwards. So Guy knocked down Cody to make him stop, letting Jessica catch up with him. Also, Guy wouldn't be jealous as it's revealed in Final Fight 2 that he has a girl of his own anyway.
Another point is that, as seen in the intro, Guy had no idea who Jessica even was until Cody filled him in.
Q] Why does the game progress onto the next stage even when there are enemies still on the screen sometimes?
The way things work in the game is that enemies will come on in waves. The trick here is to move on through a stage as far as possible, so the game sends out all the waves of enemies in that stage. For example, say a stage consists of two waves of enemies. You don't kill everyone in wave 1, and then wave 2 comes on. You kill everyone in wave 2. The game no longer cares about the enemies left from wave 1, it instead only cares about the fact that all enemies from wave 2 are gone. This triggers the game into moving onto the next part of a level, despite their still being enemies from wave 1 on the screen.
Q] Why is it that Haggar seems to just drop enemies he's holding?
A] It appears that this is a glitch. If you don't understand this question, there seems to be an issue where if you grab an enemy with Haggar and try doing his headbutt or pile-driver, he'll instead just drop the enemy instead. This glitch made it into many of the console versions.
Q] Was this game going to be called Street Fighter '89?
A] See the scans section for more info about this.
Q] Why do certain bosses grab you when they shouldn't be able to?
A] Because they're cheap. Certain bosses in the game -Edi. E, Rolento and Abigail -all have throw moves. But they can grab you without standing right next to you to get their throws in. This is particularly annoying with Abigail, as his throw can take half a life bar.
Q] Was Final Fight the first game for the CPS-1?
A] Not quite -Forgotten Worlds was the first game for the system, released over a year before Final Fight.
Q] Weren't the Mad Gear gang named after another Capcom game?
Mad Gear, a top-down racing game, had been released in Japan early on in 1989. Mad Gear was released under the name of LED Storm in America.
Q] What is Final Crash?
A] A hack of Final Fight released in 1990, created by a company called Playmark. The game itself is apparently the same as the original, just with a new title screen and some glitches with the text during the intro. SEGA may have poked fun at this in Streets of Rage 2, as a character called Shiva has a special move called the "Final Crash".
Q] What is the infinite combo, and how do I do it?
A] Soon after the game was released, a glitch was found which gave a huge advantage to any player. The glitch in question is known as the "infinite combo" and works best with Cody. To do the glitch, start off Cody's combo, and when you place the second or third hit, turn Cody the opposite direction from the opponent and press the attack button again. As soon as you do this, turn back and start to press the attack button a few times. Cody should restart his combo, but the enemy will not have had a chance to move and will keep being hit. By repeating this process, you can defeat a lot of the enemies very quickly and much more easily, and this will even work on bosses! It is much more effective in a 2 player game though, as you can have your friend cover you back from an enemy attack. This glitch also works with Guy and Haggar, although Guy's combo is seen as too weak and the timing for Haggar is to difficult for most players to perform it well.