If you have a non noble character grouped with noble characters. And are on the dungeon entry screen. And u enter with a noble character. The non noble will be teleported into the salt mine area with everyone else and can enter the cave itself. Then when you proceed approximately 1 screen into the cave you are restricted from going further. I found this by chance and it has some potential for exploitation (to gather back for multi path caves etc..) however it seemed buggy,even making it so one of my noble characters could not even be gathered into the cave. I'd recomend avoiding exploiting it for it seems to have buggy side effects.