The Samedi appearance triggers criminal violations within the Elysium areas (doesn't always happen, but it happens often enough that its put me off from playing a Samedi again), which causes NPCs to run around and not talk you. Therese pulled a gun on me after this as well. Not to mention, every time you walk out of an Elysium area after a criminal violation was triggered by the Samedi appearance, cops are swarming everywhere. My saved game also wouldn't load after I beat Hallowbrook Hotel, or any of the autosaves, but I'm not sure if that's related.