The most hated figure in the movie, Daniel LaRusso’s archnemesis Johnny Lawrence, had no backstory in the film. William Zabka, who played the notorious Lawrence, took it upon himself to create a history for the character and imagined him growing up angry about being fatherless and only ever experiencing a connection to a father figure through the equally hostile Johnny Kreese.
This created a great juxtaposition between LaRusso and Mr. Miyagi’s relationship and Lawrence and Kreese’s relationship.
Martin Kove’s Rage Lands Him the Part
Martin Kove, who played the belligerent John Kreese in 'The Karate Kid', was approached by director John Avildsen specifically requesting for Kove to audition for the role. Kove was determined to land the role, even turning down any other acting opportunities that came his way.
Unfortunately, Avildsen left Kove waiting for weeks. Kove was left irate and when the audition finally happened he let rip on Avildsen. His rage was so convincing that Avildesen immediately offered him the part!
Ralph Macchio Sabotages the Sponsorship
The Columbia Coca-Cola war was a real thing. Ralph Macchio made no bones about his despise for the marketing that was being inserted into the film. During a scene in Mr. Miyagi’s dojo, Macchio subtly blocked the Sprite logo on a strategically placed bottle.
Obviously, this did not sit well with the fizzy drink giant and the crew was forced to reshoot the scene. Macchio made sure to allow just the briefest glimpse of the logo before obscuring it yet again.
The Real-Life Karate Kids
How the storyline of 'The Karate Kid' came to be is quite a tale in itself. Producer Jerry Weintraub read a story in a local newspaper of how a nine-year-old boy came to study martial arts after a physical run-in with a gang. Similarly, screenwriter Robert Mark Karmen also found himself enrolling in martial arts classes after being attacked as a young child by a group of older kids.
Weintraub optioned the story of the nine-year-old and approached Karmen to write, making 'The Karate Kid' somewhat autobiographical for Karmen.
Bit Part Brats
A group of children bids a very warm and exuberant farewell to Daniel LaRusso and his mother in the opening scene of 'The Karate Kid'. How these kids came to be in the movie was not through casting but rather through a deal struck with the very aggravated director.
John Avildsen recounted that the highly curious neighborhood children would not stop bothering the film crew. To get them to back off, Avildsen offered them a part in the movie. Luckily the kids stuck to the deal!