I was bored today, and had a look at the Pathways Story page. After reading over the Pathways Screenshot inconsistencies again (and a bit of testing), I have a few of my own to point out.
(1) If the two differently-colored Nightmares are separate monsters as PerseusSpartacus observed, then it is suggested there are not four, but five monster types on this level. Remember killing that Headless? Of course you do. :)
I thought that a dead body could possibly be separate from its live counterpart (thus the Headless and lesser Nightmare could already be dead, and are being used as "scenery"). Experimentation (crashes) with Torch (Pathways map editor) produced inconclusive results, but suggest that they are connected, as there were no monsters but already-dead bodies of the replaced monsters in the room while I was testing. Just turning to face them crashed Pathways, so I have no visual confirmation one way or the other.
(2) The player is seen firing an MP-41, but the weapon proficiencies do not display any experience with said firearm. In the game, hitting (or simply firing at?) a monster with a new weapon immediately updates the proficiencies list. Oh but I forgot, he's actually wielding a Walther. :P