The Castle is an Australian Icon of a film and for that reason I suggest you stray away from it come HSC. Certainly its message can be quite profound if you have the ability to analyse it, but it has been popularised and is, as a result, a recognisable film-text. For that reason, markers in general will mark you a little viciously, just as they would if you used, say, transformers, or batman, or iRobot or whatever. Perhaps try for some prufrock, the island, or a profound short story or film. Check out some tropfest indie film makers - they make beautiful films relevant to belonging.
Bowling for Columbine is another film-text by Moore, but it's more so documentary style and explores a deeper message. I've never studied Navigating the Globe but perhaps it is very relevant to associated themes. Try it out.
EDIT: BFC by Moore (from a quick synopsis) explores munitions & the growing trend of violence in teenagers and kids and its effects in speeding up social decay amongst other things - but because it's a documentary where he travels to different places to explore differing opinions, maybe it might be applicable? Sorry but that's all I got
