It is a little odd that they would be releasing the recount of the vote tallies as they come in from the various electoral districts. Obviously, there are regional differences, and Obrador did better in some areas than Calderon and vice versa. So these piecemeal releases tell us nothing.
Mexico has a very secure voting system and I think it would be hard for them to manufacture votes in the tried and true Dem way (i.e., the dead-but-voting, the persons who have mastered bilocation, etc.). However, I suppose it's possible that the Mexican left has worked out some other creative way of thwarting elections.