Watching the coverage for the election, a few questions come to mind...
1) How many Taiwanese hold foreign passports and also have citizenship in Taiwan?
Technically this is illegal since Taiwanese and citizens of countries such as America are not allowed to hold more than one passport.
In reality, authorities seem to loook the other way about this but it does sometimes ignite political trouble if officials and their families do this. It becomes a question of loyalty. But let's be honest, people of all colors do this.
And why do they do it? Well, there's an expression in Chinese: "A cunning rabbit has three (burrow) holes." That is to say, make sure you have a few escape options should something happen.
In the end, it's kind of a game deciding which passport to use upon entry into Taiwan. Boys have to be particularly careful what they do in order to avoid being enlisted in the military.
2) How many people will give up their votes because they will not return to the place of their household registration?
Taiwanese, according to the law, cannot vote by proxy, that is, distance vote from places other than the place they are registered. The impact of this is a mass pre-election movement of people back to their original homes.
The north of Taiwan has a distinct political advantage due to this since many people gravitate to cities like Taipei in order to get jobs or to live. As the northerners most likely stay put, they are more likely to vote. These days the north is predominantly Blue (KMT).
The southerners have two choices: return home or stay put. If they stay put (to save the time or money or both returning), they lose their vote. If this happens in large numbers, it could have an impact on the election.