The Feral Ghoul Roamer has an error when loaded into editing software. While this doesn't cause conflicts in the game itself, the model attempts to draw from a model labeled "mmm_ghoulvariant_v1.nif". This is one of the feral ghoul variants that appeared in the Fallout 3 mod Mart's Mutant Mod, suggesting that Obsidian Entertainment had experimented with it while developing new features for the game.
Contributed by Psychospacecow