There’s a couple of good reasons one would carry a blank hard disk containing what appears to be random garbage.
For someone heading on holiday with one, it could be one they bought it 2nd hand, which they plan using for storing their photos or video footage on, which was secure-wiped by the previous owner.
For someone returning home, it could be one they bought at a garage/car boot sale while abroad, again which was secure-wiped by the previous owner.
So you could easily give an excuse like this if they question why the drive is blank. Just be sure to carry a digital camera with if you say you’ll be using it for storing photos on.
As far as I’m aware of, Turecrypt doesn’t leave a tale-tale sign for whole-disk encryption.