He can feel the gently emanation of surprise from the ghost in his chassis, and takes note of it, but the fact that this seems to be kind of bunker feels like far from the strangest thing about it to him.

Assuming their guide doesn't indicate for them to stop or turn back, he'll continue walking up and out through the tunnel, stepping gently to try and avoid provoking a tunnel collapse, and making sure to not let the top of the mecha scrape into the ceiling.

The tunnel is not in danger of collapse; it appears to be reinforced with bone, though what animal has bones in the shape of the structural members of a well-designed ceiling reinforcement is unclear. 

As Xeno leaves the tunnel, he steps into what fails to be daylight; the ultraviolet spectrum reveals that the sun is high in the sky, but a dark fog leaves what appears to be a wide flat steppe of pale grass as black as night. 

He sees a campsite of a dozen people, sitting by a fire and doing the various work of camping. As soon as they see Xeno, the cry goes up - "Monster! It must have killed the boss!" "Scatter!"

And scatter they do, fleeing into the sea of grass by every means available to them - on foot, and by mule, pony, riding dinosaur, motorcycle, and in one particularly ambitious case, by what appears to be a motorhome modified to have machine-gun positions atop it. 

'What in Hell...' Well, they're mostly certainly not in Kansas anymore. The bone reinforcements almost make sense, given what he knows now about the vechs, but this fog...

"Well, it looks like the intruder we found earlier had some friends. Let's take a look through their camp."

'If you like, you can hand me the reins and I'll keep watch and you can go take anything that catches your fancy as well. I'll keep watch of anyone coming back looking to make scrap.'

He considers it as he walks out into the midst of the camp, swapping the mecha's manipulator over to grenade launcher to pair with the spreadgun. It feels a little strange to leave the mecha in someone else's control, but if he imagines it like he's piloting it externally the normal way it makes sense to use his smaller human body for detailed searching. 'Okay.'

Once they're in place, he takes his turn talking through the loud speakers. "I'm going to open the cockpit to get out now. Try to avoid it, getting hit could hurt." His voice is kind of gravelly, and pretty deep.

And then he'll go ahead and pop the cockpit and hop out. He's big, both tall and wide, and he hits the ground with a real thud. He's not exactly young-looking, but his big eyes and the way his head is almost hairless gives him an uncomfortably childish look on an otherwise adult face. He's got a standard issue NYPD cavalry uniform on, not he recognizes it. He's also grabbed a flashlight (which he noticed earlier when searching for a sidearm) since outside the mecha he'll need to rely on his own eyes and it's looking pretty dark.