In multiplayer on hanger 18, you know how you see aliens there i think they are part of the easter egg. Seeing as the meteor that hit earth carried element 115 the aliens may have come to earth to try and contain it from zombie fying (i know it wrong) the people but they were late...... 20 years lol, but they may have thought that people wouold not have used it the way they thought it would be used eg. controlling it to be used as an undead army thus making them arrive late, as the germans experimented it, it was too powerful to be handled thus causing the out break and teleporters, with a zombie being teleported into the 60's or an alternate universe which is pretty messed up, with most of the stock pile in area 51 the aliens came to remove it at which the US managed to meet them but to experiment with them rather than working with them, with this having be done the zombie that had been teleproted into the 60's had cause mayhem apon area 51 OR the us also tried to control the zombies but fail too, thus causing a big ass break out......oh and they get teleported to the moon or experimented on there too and fails fml