In real life Henry Wickham was sent and paid by the Proyal Botanic Gardens, Kew to Brazil to collect the rubber-bearing tree seeds. In the movie he is doing it by his own will.
Don Alonzo told Mary that the island Marajo is as big as Ireland. However Marajo has an area of 40.100 km² while Ireland's area is over twice as large (84421 km²). Marajo's area can be rather compared with the size of Switzerland.
"Laternaria phosphorea" is not a butterfly, as suggested in the movie, but rather a kind of a hemiptera, a lantern fly.