As everyone else has pointed out, Liechtenstein easily makes this list, as does Kosovo, and East Timor needs to be removed. It would also be nice to lose the "an island connected to the mainland by a bridge is somehow not an island" rule and remove Singapore and Bahrain.
Seems like a pretty sloppily made quiz. Liechtenstein and Kosovo are very clear oversights, and East Timor should be removed (as should the bridge caveat, which is very arbitrary). If East Timor is included because it is connected to another country, then Brunei and Haiti also both make the list.
* Kosovo (10,887 km^2)
Not an island connected to mainland Eurasia or Australia or even other nearby islands by any sort of bridge from what I can find: East Timor
why singapore and bahrain included???? both is island