Factual error: In a flashback to his youth, one of the bullies is wearing a Bartles and James T-shirt, which is a product that didn't exist in the early 70's.
Factual error: The film was made in 1988. At that time the airport was on the mainland Kowloon side and called Kai Tak. In the early part of the film where van Damme is heading for the "East Lake Hotel" in Kowloon he is seen riding on an electric tram. These trams are only found on Hong Kong Island, which means he would have had to have crossed the harbour to reach the trams and then gone back across the harbour to reach his hotel. Fairly pointless exercise.
Factual error: In Chong Li's second fight where he splits the other fighter's shin open the South Korean flag on his manager's black sweatshirt is upside down.
Factual error: Chong Li's South Korean emblem on his headband is upside down before breaking the ice blocks. And you can see his trainer has the emblem on sideways on his arm.
Suggested correction: Someone wearing a headband, that they can't even see since its on their head, upside down doesn't qualify as a mistake and happens all the time.
While it's possible to happen, generally speaking, upside down flags or flag symbols are considered valid mistakes. Just like the patch wouldn't be sewn on sideways.
Factual error: The time period of the story has been updated from when Frank Dux claims he actually participated in the Kumite, however the scenes with young Frank take place in the mid to late 1970's. When Tanaka's son is assaulted, the clothing and hair styles worn by young Frank and his schoolmates is not period accurate and is contemporary to when the movie was filmed. One child is even wearing a Bartles and Jaymes T-shirt, a product that didn't exist until 1981.