If you're attempting to use an older version of the game to play (aka save files), you run the risk of errors.
That is because currently, backwards compatibility to saves is not possible.
It's something I either plan to address in the future, or the game will come to a point where there will be no further need to alter the variables which the player has.
I'll play through again just to see if I can find these errors, thanks for pointing this out.