When you beat the car smashing bonus stage with either Cody or Guy, a man will side step into frame, drop to his knees, and yell, "Oh, my car!". This is a reference to the car smashing bonus stage in Final Fight, where the same thing would happen if you completed it in time. This scene can also be triggered by all of the Final Fight characters in the USF4 version of the game.

Rufus' original concept art is completely different when compared to his final design. He was shown to be much slender, African American and wore martial artist robes with the words "King Cobra" on the belt. The final design was chosen because the developers wanted to leave an impression on players with his obese appearance and set him apart from the other characters.

Abel was originally female during the development of the game. Instead of traditional MMA style clothing, the original Abel wore a Kurateka (Japanese wooden footwear). A black version of the said Karuteka was given to Ken as an alternate costume, but the character was ultimately rejected.

According to Capcom's art director Toshiyuki Kamei, Hakan's turquoise, stone-like hair is a kind of pun. In Japanese, Turquoise is "toruko ishi". While "Ishi" can mean "rock" or "stone", "toruko" can also mean Turkey. This is a nod to the fact that Hakan is Turkish.

In the Small Airfield stage, Balrog will open the plane's door and spectate. If Balrog is participating in the fight, Vega will appear instead. If both Balrog and Vega are fighting, M. Bison will appear. This is in reference to their names being swapped with one-another in Japan and the west.

In a 2010 interview with the game's producer Yoshinori Ono published in the MTV Multiplayer Blog, before the release of Super Street Fighter IV, he revealed that he's a big fan of the character Rainbow Mika, and that he wanted her to be put in Street Fighter IV, especially in Super Street Fighter IV. He "basically harassed the director constantly" by just whispering in his ear "Rainbow Mika! Rainbow Mika!". Ultimately, the directors of either version of Street Fighter IV didn't listen to Ono for unknown reasons, and Rainbow Mika never appeared in any Street Fighter IV installments. She would later appear as a playable character in Street Fighter V.