Well, important to remember that everything posted here has been speculation.
Originally Posted by OliveOil_Med
Canonically, we know very little about Apparition or Portkey travel. It may well be that wizards can Apparate to the moon. It may also be that no one can Apparate more than a few miles.
We can make reasonable suppositions (I've outlined my reasons why I think the range of Apparition/Portkeys is relatively limited), but if your story needs for wizards to be able to Apparate between continents, you won't exactly be contradicting canon to make it so. But some readers (like me) may find it a little implausible. I have a hard time believing that wizards can just hop from England to Australia in one trip, for example. But if you established some special conditions under which it is possible (you have to be really powerful/it's extremely risky/there's a special super-Apparition spell that requires a bunch of wizards and a Portkey to cast/etc.) then it might be more believable.