Just stumbled across this while looking for some Air Vanuatu deals, and found Virgin Australia is currently bookable for dates in 2021 from $222.66 RETURN to Vanuatu. Other vendors seem to have it at over $500 so it certainly appears to be in error.
Warning: All error fares at your risk. Sometimes airlines will honour them, sometimes not. Read all the terms carefully. You might just end up with credit. And with covid, who knows what the borders will do.
Sample date in evidence - Feb 6 to Feb 13, 2021.