Apologies for the necro-post, but I managed to reproduce the final boss glitch. I've uploaded a video here:
Link to videoIt seems that if you land a hit on the boss as the sword he throws is about to hit the wall, it delays the impact significantly. Using this, you can defeat the boss in one round! II haven't been able to reliably reproduce this, so there may be other factors (possibly opening the menu?)
EDIT:
Under normal circumstances, the sword the boss throws rotates as it flies. At the time it reaches the wall, the game checks to see if the sword is pointing directly towards or diagonally towards the wall. If the sword is pointing in any other direction, it rotates in place then impacts the wall.
However, if you hit the boss before the sword hits the wall, the sword stops rotating. If it is pointing towards the wall (straight or diagonally) it will impact as normal. If it's pointing in a different direction, it will jam in place for a long time before it starts rotating again to impact the wall.
Doing this, you can defeat the boss in one round! Jamming the sword gives you just about enough time to do this before he finishes retrieving the sword. If you're playing this in real-time and miss a bubble-gum shot, you'll need to land the last two shots in the next round to finish him.
Hahaha, yes! A great improvement, and remarkable use of both characters to bypass enemies. Great to see there was a lot less backtracking too.
Would be a yes vote if I hadn't been lazy and just registered. >.>