Revealing mistake: When "Krebbs" the koala is discussing with his other friends in the cell. If you look closely, you can notice a blink in the outline in the "Krebbs" nose. It's a clear ink & paint mistake of the blur line.
Continuity mistake: When McLeach pulls Cody out of the hole, the distant shot of them (where the Bushwhacker vehicle is shown to the left) shows a golden feather in McLeach's akubra hat that does not appear in any other shot until McLeach subsequently takes the one from Cody's backpack and fits it onto his hat. This is not McLeach's own feather because that is later revealed to have been stored in his vest. (00:12:15)