Well, the criterion for the list was weapons that "truly changed the course of human history". By that definition I'd say the Panther tank is out - it did not really change anything.
Also, the list on the show was specifically for post-WWII weapons only, so the submarine was excluded on that basis alone. Even then, there was clearly some fudging going on anyway. Although the AK-47 was in there, it's conceptual origins and even prototype design actually began before the war was over. And while the carrier was developed, obviously, before wars end, they still put the Nimitz "supercarrier" in there as being sufficiently distinct (which was pretty lame, IMO, as the real advance in carriers came about during the war, not after it - the supercarrier is just an extension of that development). By that criterion, nuclear subs should have been in there too, despite the origins of submarines, as nuke boats represent an even greater evolutionary step over conventional boats then nuke carriers do over conventional carriers.
But hey, it's television, so what can you expect
The list has also got a largely subjective aspect to it too, since the list was limited to only 10 weapons. I guess they just realized they had to put some boundaries on it or it would be impossible to compile any kind of short list.