Theory:Doctor Who television discontinuity and plot holes/Planet of the Spiders


 * If the spider is on Lupton's back in episode two, why isn't it squashed when he sits in the various vehicles?
 * Presumably it was slightly 'out of phase' with the rest of the universe, meaning it was intangible as well as invisible, i.e. perhaps in a similar way as the Master used to make the Doctor's TARDIS inaccessible to him in 'The Keeper of Traken'.


 * During this epic chase, why doesn't Lupton simply disappear as he does at the climax?
 * He wasn't near enough to the monastry earlier on.


 * This isn't the same sonic screwdriver as in Carnival of Monsters, so why does Clegg associate it with Drashigs?
 * Perhaps it contains some of the same elements, battery etc., salvaged from the earlier model?