Per an answer to this question about capturing a Tarrasque in a Wall of Force sphere, it seems the Tarrasque can use Swallow on a caster, who can then cast a Wall of Force spell inside the Tarrasque.
The description of the Wall says (emphasis mine)
Nothing can physically pass through the wall. It is immune to all damage and can't be dispelled by Dispel Magic. A Disintegrate spell destroys the wall instantly, however.
Does this mean such a Tarrasque would have its movement limited by the swallowed Wall? It seems the alternative is that it can move around a spell effect with physical force, which seems wrong to me.