For class, I was searching google images for drawings depicting impossible moons. I’m pretty sure this one wins because of its irony with the title. Note that I haven’t read the book.
My thinking:
#1 You can’t see a crescent moon with this orientation at night time, because the sun would have to be in the sky (i.e., above and to the right), thus making it day time.
#2 The star to the bottom left of the crescent shouldn’t be there due to occultation–the dark side of the moon is still there, blocking our view of that star.
Teach. Brian. Teach. 
this is awesome! I’d love to know if the author approved or just had it forced on him.