User blog comment:Zathronas/Analysis by an author: Penny/@comment-12227301-20131215013134

So, we see Penny "anchor" herself to the building behind her some time before catching the ship and we don't see her remove the anchors. However, the scene where she pulls the ship has her far from the anchor's wall, so that may be a rebutal, and is probably a mistake.

Guess 2 would be that an Aura power is involved, though that would require Penny to have a soul, something we're unsure about.

A last point is that the blades seem to be able to move on their own, through telekinessis or somesuch. Perhaps the blades themselves offered the force to move the ship, with no "reaction" on Penny.