Yeah - that's the area I was thinking of. (You can't actually go into the bathrooms... er, that I am aware of... there's just a sign that mentions the bathrooms are in that direction).
And you've gone back to all the places - guys from Andromeda's landing? The desert, you have - because you mentioned the worm. Um, Crash's place - outside and inside?
Trying to think (I don't have them all myself, but been collecting them) - I can't think of any that are specifically "hidden" except the asteroid ones?