Kingdom Hearts HD 1.5 ReMIX

GLITCHES

EXP. Zero Damage Storage Glitch (Kingdom Hearts Final Mix)
Exclusive to Kingdom Hearts Final Mix on the ReMIX versions of the series, Sora starts Proud Mode with the EXP. Zero ability available. This ability negates all EXP. gains - allowing for Level 1 Proud challenge playthroughs - while rebalancing the game to make various battles difficult but not unwinnable. The rebalancing mechanics lead to a glitch known as "damage storage," however.

In essence, during various battles (bosses in particular), your damage output is corrected on each hit to better fit the zero-EXP format. However, the finisher for your aerial combos has a much higher correction than normal to do extra damage. While most attacks reset the corrections to your damage as intended, Magic and Summons do not. To abuse this oversight to great effect, do an aerial combo finisher, and then use magic/summon attacks, and you'll find that you deal much more damage than you otherwise would. The effects of this glitch will persist until you make any further attack with your Keyblade, after which the damage acts as normal (unless you do another aerial combo finisher).

Unlocking the Speedstar Trophy for Kingdom Hearts: Final Mix After Passing the 15 Hour Mark.
If you have already passed 15 hours of playtime on your attempt to get the Speedstar Trophy, their is another way to get it. When your in-game clock gets to 99:59:59 it will reset back to 0:00:00 and change colors from Blue to Green. This is supposed to let you know that you have played for over 100 hours. However, the Trophy will read the actual game time, which will show as below 15 hours. All you have to do is defeat the final boss before it passes the 15 hour mark again, and the trophy will unlock.