Fictionalized Underground Seattle goof

As I mentioned in my previous post about the Hollywood fictionalized depiction of Old Underground Seattle, Kolchak entered the lair of the insane, undead alchemist, former Union Army officer and doctor, Doctor Malcolm. The props department scattered all sorts of 19th century-type props and objects around. Also scattered about were trees and bushes. That is the GOOF. Trees and bushes could not have grown underground in the absence of sunlight. Still the whole scene was well-played out. It was eerie and spooky and no one in his right mind would have ventured down there.