So does JetPunk recognize the border between Bahrain and Saudi Arabia or not? Because I always thought you didn't, but if you're recognizing the island as shared, then shouldn't there be a border? There's a guy who used to drive across that causeway once a week who would've told us all about how the McDonald's on the KSA side closes at prayer times but the McDonald's on the Bahrain side doesn't. Takes you back, man....
Also, you should probably add a caveat stating that lake islands & river islands are not considered. Otherwise, this list gets a bit messier.
Wikipedia article
Although this is a river island, perhaps as cta127 says, add a caveat to not include river and lake islands.
Source: I'm Finnish.
https://en.wikipedia.org/wiki/Overseas_collectivity
https://en.wikipedia.org/wiki/K_Island