Here is my theory, Moon, NukeTown, and Tranzit is connected I'll tell you how. You remember those three missiles from moon when you do the easter egg? well one of the three are found in Black Ops 2, don't believe me I'll give you more evidence when you lose on NukeTown the ending cut scene has a missile hitting NukeTown you know what that missile looks like? the one from moon! that means moon and NukeTown take place in the same year, so you're probably asking how does Tranzit connect to this? Well if you knife the bomb shelter you can hear Marlton's voice and that means he was there and also there is a bomb shelter behind the bus depot in Black Ops 2 which means the one in NukeTown and the one in Tranzit are the same one.
hm, that's a good theory and reasonable