Theory:Doctor Who television discontinuity and plot holes/Underworld


 * The climax to episode one relies on some very odd ideas about the laws of gravity. Particles of rock would not typically be attracted so rapidly to the hull of such a small spaceship, unless some additional force(s) were at work.
 * Like the electromagnetic force? Maybe the ship uses some kind of ion drive or other mechanism which leaves its hull strongly positively charged (with the charge proportionate to its mass). And maybe whatever a 'spiral nebula' is supposed to be might negatively charge the rocks. In which case, the whole thing would just barely make sense.


 * How does firing the ships laser canons (presumably in a fixed direction) shift the rock from the whole of the hull?
 * They never say that they're firing in a fixed direction—and the fact that they're beginning to burn through the hull implies that it's not a fixed direction, they're pointing them inward to target them at the ship.


 * On the other hand, if the problem is electromagnetic in the first place, a laser might be a good way to solve it. Blast a bunch of rocks and dust into plasma and they'll attract the other rocks more strongly than the ship does.


 * Herrick is shot several times by laser beams, yet not only survives but after he is rescued from the Oracle's lair, appears to be in perfect health, as opposed to all of the guards who appear to die instantly from single shots from similar weapons.


 * What exactly is a 'spiral nebula' supposed to be? In the real world, it's an obsolete term for 'galaxy', before we figured out that they were galaxies in the early 1920s. Flying into a galaxy isn't going to cause much of a problem, considering that the edge of a galaxy is far less dense than the space within our solar system.