After reviewing all of the concept art materials, two items jumped out at me:
1. The rendering of the makeup experience in Dr. Pretorius' old lab features a conspicuous amount of jars...
Potential for some of Dr. Pretorius' tiny people experiments from BRIDE OF FRANKENSTEIN to appear? I'd think that would be a pretty easy projection effect:
2. The "Beware of the Moon" artwork before the first launch on Curse of the Werewolf prominently features this wolf/pentagram symbol...
... which is the symbol on Larry Talbot's silver-headed cane in THE WOLF MAN...
Nice touch.