As Grace and Adam pull on the rope of the boat, the rope extends horizontal to the water surface (away from them), but in the zoomed-out shot, the rope goes down to the water.
While in the tree, Adam says they'll die of malaria because of being bitten by mosquitoes--except that before it was banned, DDT was used extensively in Australia to eradicate malaria, as part of a World Health Organisation program in countries with low transmission rates.
31 mins, 44 secs. in, a noise is heard that sounds like a car-horn honk. This would not be possible if they were stranded in a mangrove swamp, away from civilization.
When two characters are sitting in a tree, a crew member's arm is in the bottom right of the picture.
When Lee heads for safety, she appears to be traveling upstream. Not only is this hard work, against the current, but it also overlooks the fact that almost all the population of Australia lives on the coast. She would be heading away from help, into the vast interior wilderness.