Just in case it helps Ade, here's a list of bugs I'm familiar with from the original edition.
Crash: Displaying a Super Jets total over 2.1 billion (2^31) crashes the game. (Only when displayed, not during a frenzy.)
Crash: End of Time total over 2^31 is always displayed as garbage and sometimes crashes the game.
Overflow: Bonus over 2^31 overflows into negative and subtracts from your score instead.
Wizard modes count as drains: At conclusion of a failed Timeshock Frenzy or any End of Time, the game behaves as if you drained a ball. Your bonus X and super jets are lost if not held, or reset to unheld if held. Super Magnosave is lost.
Freeze: On the Video Mode total screen when pressing the launch button to skip it, I've had the game freeze sometimes. It's not reproducible reliably but has happened to me several times. I suspect it happens if you hit launch just as the screen is timing out of its own accord. Not a high priority but worth a look if you happen to be around that area of the code.
Souvenirs: If you have a souvenir pair collected but not yet redeemed at the Scanner, and collect both souvenirs again, you can still only redeem the pair once and lose out on the second. (This could be intentional but I don't see any reason for it to be.)
Upper ramp: Sometimes you don't get credit for an upper ramp shot if another ball from the plunger is going up the ramp very close. I understand that's realistic thanks to switch debouncing, but would be nice to adjust that sensitivity or compensate with other switches.
Continent count: Something can credit an extra continent towards the game total, more than 8 in one time zone. I don't know what causes this. But I've seen it as 86 continents searched when I know I went to only 10 time zones (should be 80 continents.) Obviously very minor.