KingG: Wow! In a completely lost position, Kasparov just goes for a desperate attack against Black's king, and gets away with it!
After 33.Kg3, Fritz gives the evaluation 9.42!!
The first real mistake after that was 36...Bxf6?, which was completely unnecessary, as <offramp> points out above.
Then Kasparov makes a mistake of his own with 38.Kxf2?, when 38.Qh8+ would probably draw after the exchange of queens.
And then, Korchnoi misses 40...Be5, which is obviously completely winning. I can only imagine the Korchnoi was down to a few seconds on the clock to be able to miss that.
The final mistake was 41...Qf6? which throws away any kind of winning chances, although the position may still be drawn.
This game kind of reminds me of online blitz games(or in fact, any kind of blitz game) where the player in a lost position becomes desperate and start playing all kinds of crazy moves in the hope of swindling his opponent. Obviously, this is on a higher level, but that's the overall feeling i get from this game.