I assume by "RW" you mean "RTW" ('Round-The-World)

I do not believe your routing would be allowed on the OneWorld Explorer RTW fare. The problem is that once you depart Europe for Mauritius (which I believe is in Africa...) you cannot return to Europe (without circling the globe first). There are a few "dead end" cities in Africa that allow re-entry into Europe per the OWE fare rules, but I don't beleive MRU is one of them.

Besides, do any OneWorld airlines even fly to MRU? I spot-checked ITN and couldn't find any flights...