Apple's iOS 6 Maps app has been the subject of some well-deserved criticism, but any mapping platform will come up with odd suggestions if you throw enough queries at it. Google Maps, for instance, will offer you driving directions to Sydney to Los Angeles — via Japan.
Inspired by Google Operating System noting that Google Maps now routes directions from the US to Europe via the Pacific Ocean, I decided to check what it would offer for a US-Australia pairing. The system is intelligent enough to know that you'll need to sail across the Pacific Ocean to do that, but for some reason opts for going first to Hawaii and then to Japan rather than straight between the two continents. It also helpfully notes "this route has tolls".
The same directions are offered for pedestrians and cyclists. If you actually want to find ways of moving between countries that don't necessarily involve a plane, rome2rio is a good place to start.