Couple notes though, take into account where the majority of JetPunk's user base is (overwhelmingly North American and the rest is mostly Eastern European). Consider what they're more likely to know, for example I think North Americans are more likely to guess Vancouver and possibly even Baffin than Borneo. Madagascar is also definitely more well-known as an island than Borneo, it being a country and all. Honshu is probably less identifiable to Americans than Madagascar and even Borneo.
Of course, these are just subjective answers, if you want a more quantitative approach I'd take Neo's suggestion and start reordering the answers based on answer stats.
I spelled Mindanou exactly how it should be spelled and the way you have it on the test. But it would not accept the answer? That is a great quiz! I wish there were more like this one?
Couple notes though, take into account where the majority of JetPunk's user base is (overwhelmingly North American and the rest is mostly Eastern European). Consider what they're more likely to know, for example I think North Americans are more likely to guess Vancouver and possibly even Baffin than Borneo. Madagascar is also definitely more well-known as an island than Borneo, it being a country and all. Honshu is probably less identifiable to Americans than Madagascar and even Borneo.
Of course, these are just subjective answers, if you want a more quantitative approach I'd take Neo's suggestion and start reordering the answers based on answer stats.
Oh and by the way, #47 (in Australia) appears giant when it comes up. Might want to look into that!