Mirror, Mirror… Wherefore art thou, mirror?

I was recently chatting with Dr. David Nacin, a fellow puzzle enthusiast who has taken a keen interest in solving, studying, and sharing my Haunted Mirror Maze puzzles. For the uninitiated, Haunted Mirror Maze puzzles present a top-down view of a hall of mirrors. The mirrors are aligned to a grid, and empty spaces must be filled with some number of vampires, ghosts, and zombies. However, Dr. Nacin relayed a query he received in the course of sharing the puzzles:

An interesting idea. Someone asked if the mirror squares were always given in the monster maze puzzles.