Can non-exile related return effects bring a card out of exile?
Karakas' ability:


  Tap: Return target legendary creature to its owner's hand.


Karakas returns a creature. Creatures only exist on the battlefield, everywhere else they are usually creature cards (or spells, on the stack).


  109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but doesn't include the word "card," "spell," "source," or "scheme," it means a permanent of that card type or subtype on the battlefield.


So Karakas can not target cards in exile.