Ones with the cone front seem hard to find. Also from the movie stills the front defuser is completely transparent. Not the translucent ones that seem more common, and not the dome ones that are even more common. Some interesting literature on the operation of the real sight.
http://soldiersystems.net/2015/11/20/sof-carbines-comparing-the-son-tay-gau-5aa-and-the-m4a1-cqbr-part-ii/
http://shootery.blogspot.com/2010/07/moldy-oldie-review-singlepoint-sight.html
http://seanlinnane.blogspot.com/2010/11/son-tay-raid.html
http://www.ar15.com/forums/t_3_123/649246__ARCHIVED_THREAD____Single_Point_Sight.html&page=2
http://soldiersystems.net/2015/11/19/sof-carbines-comparing-the-son-tay-gau-5aa-and-the-m4a1-cqbr-part-i/
http://www.ar15.com/forums/t_3_123/649246_Single_Point_Sight.html&page=3
They are really not scopes as much as the predecessor to the red dot sight.