The "Combo" system developed for the game was a bug. A bug in the game's code enabled the player to "cancel" during the animation of some moves by performing another move, allowing for a combination of several basic and special moves. This "combo" system was later adopted as a standard feature of fighting games, and was expanded upon in subsequent Street Figher installments.

In Japanese versions of Street Fighter II, M. Bison is called Vega, Vega is called Balrog and Balrog is called M. Bison. This was to avoid any issues over naming Balrog, the boxer, a name very similar to that of Mike Tyson.

In the first three versions of Street Fighter II, "World Warrior", "Champion Edition" and "Hyper Fighting", Ryu and Ken's Hadoken sprites would sometimes appear orange. Developer Akira Nishitani confirmed that this was added as an Easter egg, and wasn't a glitch as previously thought.

In later versions of the game, starting with "Super Street Fighter II: The New Challengers", Ryu would receive a legitimate orange Hadoken special move called "Shakunetsu Hadoken"

In every Street Fighter II version in which Vega can be selected as a playable character, the Spanish flag seen in the character select screen is the one that was used during the military dictatorship of Francisco Franco (1939-1975).
This game was released in 1991, 16 years after that flag was declared unconstitutional.

Akuma has two different endings depending on whether the player beat M.Bison or Shin Akuma. The text in both endings was removed in releases of the game outside Japan.

It was initially planned for special moves to do more damage the quicker the command was entered.

In the Japanese versions of Street Fighter 2, advice is given to the player on the continue screen. The developers originally considered having a mysterious old man give the advice, but never decided on a design for him, and so the idea was dropped.

Blanka's Rolling Attack's command was originally charge down, then forward. This felt wrong, as it was different from the rest of the game's commands, and so it was changed.

The idea of Street Fighter II Turbo: Hyper Fighting came about as a result of Capcom USA's James Goddard testing the counterfeit "Rainbow Edition" at an arcade to see if it represented a serious threat. He was initially unimpressed by the poor balance, but Champion Edition "felt like it was underwater" after experiencing the faster pace of the counterfeit.

Some fans have pointed out that Ken's theme sounds similar to the Cheap Trick song "Mighty Wings" from Top Gun. Street Fighter 2 composer Yoko Shimomura stated in a interview: "I have heard people say that, and I watched the movie before I composed the song, so I can't deny I may have been inspired subconsciously. But I didn't go into it thinking, 'OK I'm gonna make this song sound like Mighty Wings.'"

In the Super Famicon version of the game, a man in a blue coat and hat can be seen in the background of Ken's stage moving his hand up and down in front of his crotch. This was changed in international versions due to the movement making him look like he is masturbating.

Two non-playable fighters are shown during the opening scene of Street Fighter II: World Warrior. One punches the other, followed by the screen scrolling up a skyscraper to display the game's logo.

The fighters' names were revealed to be Max and Scott as part of Street Fighter V's "Shadaloo Activity Report" on Capcom's Japanese website.

Chun-Li originally had a back flip attack, but it was cut due to being too strong and the team not having enough time to adjust it. However, sprites for the move still exist in the game's data, and it was later implemented in SFII: Champion edition.

Zangief's headbutt move was originally more elaborated, originally being a throw in which Zangief sent the opponent straight into the air and would then headbutt them on the way down. It was cut due to issues implementing the attack.

The team originally wanted to introduce special KO animations depending on how the player finished off their opponent. The only remnants of this feature are a special KO if the player's character is defeated while guarding against a hadouken.

Super Street Fighter 2 HD Remix started out as a remake of Street Fighter Alpha 3. Lead designer David Sirlin felt that Alpha 3's large roster would make the development process more difficult. He also believed that the game's lack of approval by the hardcore community would harm the game's sales, so he pushed Capcom so that they could work on SF2 instead.

David Sirlin also confirmed that the development team scrapped 2,500 animation frames in development because they weren't satisfied with how they turned out.

The team originally wanted to give Dhalsim the ability to use the attacks 'Yoga Mummy' and 'Drill Kick' in reverse so that players could retreat. This feature was removed because the computer AI didn’t know how to handle it.

During the development of Street Fighter II, an early design for Dhalsim bore a striking resemblance to Ganesha, a Hindu god with four arms and the head of an elephant. His name around that time was Naradatta’, which may refer to a character in Osamu Tezuka’s manga Buddha.

During the early development of Street Fighter II, many characters had placeholder names until they were given proper ones:
•Zangief was referred to as “Vodka Gorbavsky".
•Chun-Li was named "Chinese Girl"
•Blanka was called "beast"
•M.Bison (Dictador) was named Washizaki (鷲崎 "Eagle Cape"), likely a reference to the villian of the same name from the manga series Riki-Oh.

Early sketches suggest that Vega was going to resemble a medieval knight wearing a full suit of armor. He was also simply named "Spanish Ninja" by the developers until he was finally given a name.