It look like jbhifi have pulled a technicality by including a online competition and becuase of that says its a jb exclusive.
Jbhifi
https://www.jbhifi.com.au/movies-tv-...s-last-knight/

I preordered mine from sanity which says it includes a bonus disc and i will be deeply annoyed if the bonus disc is exclusive to jb hifi.
Sanity
http://www.sanity.com.au/Search?sanq...0last%20knight

The other stores have it as well
Mighty Ape (Au)
https://www.mightyape.com.au/movies-...he+last+knight

Ezydvd
http://www.ezydvd.com.au/search?q=Tr...+knight+&t=all