I would say that the tourament is fairly unrealistic. Apart from the level of savagery which is unlikely in a tournament of that age category it suffers from too many 'big' moves. I have fought several times under various rule formats and the moment I see a large 'flowery' move I, basically, run forward and throw punches. Their technique does not land 'cleanly' hence they do not score and as it does not land cleanly it rarely hurts. A genuine combatent would not stay in at the correct range (or conveniently move to the correct range) long enough for the majority of these techniques to land unless the skill difference was absolutely massive.
Movie combat is very rarely realistic because realistic fights are quick, graceless and over pretty quickly. Martial art tournaments normally have fighters sticking to a few techniques they know well which optimise the rules set but are rarely as clean and polished as you would see here. The original Karate kid had far more plausible tournmaent fighting (apart from the Craine kick - your opponent would simply move the side and charge in) and also tournament admin (although that is not what you are asking I guess).
From the insultingly stupid movie physics website:
A western style boxer must move to within an arm's length of his
opponent in order to land a punch. The punch's time of travel to its
target will be less than 0.1 second--barely enough for an opponent to
see it coming let alone respond. Needless to say, if the opponent's
arms are even slightly out of blocking position or he fails to realize
that a punch is about to be thrown, he's going to be hit.
Likewise, if the person throwing the punch misjudges the location of
his target or it unexpectedly moves, he's going to miss. Mid-course
corrections of a punch are next to impossible to make. If the puncher
develops the bad habit of preceding his punch with any type of
unnecessary motion, such as slightly pulling his hand back before
striking, he warns his opponent that a punch is coming. It's going to
be blocked. Although punching looks simple, it takes countless hours
Properly throwing the punch is only part of the requirement for
winning. Boxers bob and weave in seemingly random ways to confuse
their opponents but also because moving targets are harder to hit. It
takes a considerable amount of strategy involving jabs, feigns, and
footwork to set up the openings required to land a powerful punch. If
the the punch fails, the boxer is now in range for a counterattack.
Some martial art styles completely avoid high kicks for just such
reasons. To reach an opponent's face, a foot has further to go than a
punch, thus taking more time, which a defender can use to detect and
For the final dramatic kick in the movie, the current karate kid
(Jaden Smith) stood perfectly still then jumped upward, rotated his
body, hit his opponent in the face, and ended with a perfect landing
after a 360º flip all using only one leg. Like the boxer, before
making his move, the current karate kid would have needed to
accurately estimate the final position of his moving opponent to
actually hit him. His ability to alter his trajectory in the middle of
the kick would have been limited. Likewise, his timing would have
needed to be perfect. If the kick were executed a little too soon or
late it would have missed. Compared to a punch, his opponent would
have had lots of time to see the kick coming and respond.
When the foot found its target some of the kicker's rotational
momentum would have been transferred to the opponent. The more
forceful the kick the greater the loss of rotational momentum, the
more momentum lost, the greater the chances that the rotation and
landing could not be completed. Of course, choreography, dramatic
music, sound effects, camera and editing tricks along with wire work
can make even non-martial artists look like power rangers.