The emu should have been in it over the cassowary, yes, but omitting the koala wouldn't have been wise I don't think. They are almost as popular as pandas in the zoos that have them. Looking at your list on your earlier post, in the nicest way possible a kangaroo, wallaby, tree kangaroo, and emu makes for a pretty sad pack for Australia's first (and possibly only) outing.
The best version of the Australia Pack I think is the kangaroo, emu, koala, Tasmanian devil/wombat mix. I swing for the devil because it's endangered.