One loose end... (spoilers)
Having watched the entire series now, one thing is bugging me.
In Season One, when Lena is on the farm with Serge she begins showing the signs of being one of the returned – she develops those same bleeding sores as the other ghosts/zombies when they are too far apart from each other. This is never referred to again and it is obvious by the end of the Season Two that Lena is not dead.
I am assuming that maybe there was originally going to be a twist where it turned out Lena was really dead, but that this was later abandoned some time in the three years between Season One and Two.
Unless anyone has another explanation?