Okay, I saw this video the other day:
The zombie seems to zipline to the drop to get to the mp40. Other people claim to have george or a zombie zipline from the boat to the ak74. I've never experienced this myself. Its either simply one of the many game glitches on this map or it could be glitched in a way that it shows us a secret on this map that hasnt been discovered yet. Maybe there is something zipline related that we are missing. Anybody have any ideas?