Continuity: At the end of episode two, when the sink is emptied, the plug is placed on the bench. In the reprise for episode three, the plug is put back in the sink (thus enabling the miniaturized travellers to escape).

Plot hole: The miniaturized TARDIS crew never interact with the other characters in this story, because, as the Doctor points out, the 'giants' will be unable to hear them, as their voices will be on a different wavelength. So why does the Doctor later suggest using the telephone to try to call for help?