On the character select screen in the arcade version, Chun-Li is shown in a pink outfit, despite the fact that she fights in a blue outfit (corrected in Super Nintendo version.)
On the character select screen, Zangief is wearing a tank top, but he fights shirtless.
The flag of Spain (which appears for Vega's/Balrog's stage) on the map of the character select screen is incorrect; it's from Franco's regime (identifiable by the coat of arms), which was replaced with the present-day flag in 1975; sixteen years before this game was released.
The time zones and time of day do not line up consistently between characters' stages from different locations in the world. In the United States, Ken's and Guile's stages according to the map are located in the Eastern time zone at daytime, Balrog's stage that's in Las Vegas at night is in the Pacific time zone that's three hours behind the time zone of Ken's and Guile's stages. Chun-Li's stage on the other hand that's in China while set during the day is 13 hours ahead of of Ken's and Guile's stages in the Eastern time zone and should be at night if Ken's and Guile's are during the day and vice-versa.
One of Guile's victorious quotes, he sometimes says "Go home and be a family man!", regardless if his opponent is a male or female.