Headscratchers / Time Lord

I know TARDISes are bigger on the inside, but...
How would Tohno Shiki be able to enter his TARDIS (i.e. a knife) when the entrance is several times smaller then he is?
Why is the Warden's TARDIS Superjail?
Superjail is a series of buildings and made into a volcano. Shouldn't Jailbot be his TARDIS?
  • Because even if then the jail is still bigger on the inside.