Daniel's Apartment is called "The South Seas," located in Reseda, CA.

Ralph Macchio has almost no sense of smell at all. Just for fun, he makes it a point to smell something at least once during every movie he's in. In this movie, he smells a french fry at the restaurant, and he smells his underarm before approaching Alli.

Pat Morita (Mr. Miyagi) never learned karate.

Daryl Vidal created the crane kick for the movie and was Pat Morita's stunt double during the scene where Miyagi is perfoming the crane kick on the stumps.

William Zabka (Johnny) produced a band who realeased a single titled "Sweep the Leg Johnny". The name comes from Kreese's infamous line at the end of the movie and the video for the song includes Karate Kid cast members William Zabka, Ralph Macchio (Daniel), Tony O'Dell (Kobra Kai Jimmy), Rob Garrison (Kobra Kai Tommy), Ron Thomas (Kobra Kai Bobby), Martin Kove (Kobra Kai sensei Kreese), and Erik Felix (Kobra Kai student Robertson).

The name Miyagi and the karate style he used are based in truth. The real Miyagi lived in China and combined Okinawan techniques with Chinese kenpo to create the Gojuryu style demonstrated in the movie. However, many of the moves performed, such as the "crane kick", were created solely for this movie and do not exist in the style.

There only actual black belts in the cast are: Daryl Vidal (Johnny's semi-final opponent), Pat Johnson (head official for tournament), Chad McQueen (Dutch), and Ron Thomas (Bobby Brown of the Kobra Kai).

An original draft of the script had Bobby quit the Kobra Kais by throwing his belt down in front of Kreese and walking out of the arena after the injured Daniel was taken to the medical room.