This is just the exterior or the case. there are no "internals" holding things in place. I'd guess the buttons are not connected to anything and just free floating, or placed very carefully so they don't fall out.
arn
This does not explain the rotation of the volume "-" button. The photo of the volume button part from ilab shows the "+" and "-" buttons as a single connected piece. Therefore unless the buttons were separated and rotated or different buttons were used, I'm not sure whats going on here.

This anomaly is very strange as it only occurs in one of the photos. The image doesn't appear to be altered and the parts appear genuine to me so I am a bit confused.