well sunrise plan was to tell that the Ship(zero's) is purposely placed there by zero to make sure that even if the britannia's fleet surrounds the harbor the subs still have a way out.
why they don't shoot zero and why zero does not fell from vincent hand's, it's due to the Plotarmor. and not all of the absurdity is coming from the plotarmor, kay.
and Physics in Geass? yes there is, even if the physics was coated in fictions upgrade. it happens in most of real robot themed anime (geass, gundam, macross, evangelion, and many more)