Played a little more.
New high score, 807,150 Level 27. At least two flasks complete for 200,000 bonus. I think 2 big fruits dropped.
Remembering why I played this so much back in the day. Brilliant game.
On the C64 my mate and I used to play 2 player and got so much further than this as it was too easy to continue using the second player. It was about getting further, not about score. We'd play until we both died at the same time. Still we were able to get to the top of the screen using our own bubbles, something which I can't seem to do here.
As far as I can tell the massive fruits are triggered by the staff rod thing item that appears, which in turn requires some event to occur.
The game counts the number of times you do stuff. To get flasks for the 100,000 bonus you need to drop out of the bottom of the level and appear at the top, some 15-18 times. Some levels you can bubble up some enemies and with the red shoe drop bottom to top around 5-6 times before they need to be popped. Just try not to make this happen on the level with the heart in it as that can be a total waste.
I also read somewhere that the game gets harder if you get too many lives.