No one has been arrested over the incident and no threats were received by the airline.
The 180 passengers were interviewed by police and given overnight accommodation in Melbourne hotels.
Baggage on board the flight was also removed and screened.
Air Mauritius' Australia manager, Steven Palombo, said the direct Melbourne-Mauritius flight had been rescheduled for 11.30am (AEST) Thursday.
He backed the pilot's decision to return to Melbourne when the can was discovered.
"I think safety is number one and I think the captain absolutely did the right thing," he told AAP.
Police said the captain of the aircraft acted appropriately.
- AAP