Continuity mistake: At the time of the evening check when the girls are found missing the sky is dark and overcast. Then it cuts to the girls running through the forest and the sun is shining again. Also when Moodoo the tracker discovers their footprints at the outhouse (quite a feat considering the number of girls which have left their tracks around there) the sun is shining.
Revealing mistake: When the three girls are at the camp for children after being removed from their home, they witness a girl being punished. She is having her hair cut off and is put in a tin shed. If one looks carefully, one can tell that the child inside the tin room is actually a boy with a slight mustache.
Deliberate mistake: When the girls are shown at home at the beginning of the film they speak in their native tongue except when they talk to whites. Also at Moore River they get sometimes scolded for using that 'jabber language'. Therefore, it seems wrong that on their walk home they talk to each other only in English. (Though the director admits on the commentary that he felt this would be unrealistic, he decided the audience would connect with the girls if they speak English rather than reading subtitles.)
Factual error: The film is set in Western Australia during the early 1930's. The aboriginal children are being transported to a government mission by train. The scene shows a famous steam locomotive "3801" built for New South Wales Govt. Railways in 1943. This locomotive is now well known in Australia. It made the record breaking trip for steam across the Continent to Western Australia after the trans continental railway was completed in the 1960's.