The SWG team made a minor update today regarding the Galactic Moon Festival:

• NPC responses to "Trick or Treat" should now only be heard by the player that said it, not other players in the area.
• You should no longer lose your costume when you use your ship to instantly travel to another planet.
• Regions that are permanently night for this event should actually stay that way now.

Good news about that last one. Nothing's more disconcerting than a sudden sunrise. Trick or treat!