Scary aliens! Are these creatures going to appear in the book?
As for the dark picture, why need a flash, you could just adjust the exposure settings. Also if your camera is advanced enough, you could just take a HDRI picture and adjust the exposure afterwards and even do some cool stuff.
By the way, isn’t it dangerous in such darkness. With such uneven floor and those steps and such, you are very likely to trip over.
If you want some critique to your CG work, well that is a different matter.