Jackson used duct tape to temporarily repair the leaking fuel line. Avgas, like gasoline, is a strong solvent, and would dissolve the glue on the tape, on contact.
The ferry from Mauritius to Rodrigues is actually 37 hrs long not a couple of hours as mentioned in the movie. The pilot also mentioned that the flight to Rodrigues will take 90 mins and so it's not possible a ferry will take just a few hours. And Air Mauritius does fly to Rodrigues, 4 times daily on ATR-72 with 74 seats.
The airplane in the movie is a GippsAero GA-8 Airvan.
Island/sandbar they end up on is Vlasoff Cay in Australia.