Powder Keg is built around the Marvel Cave theme, though this really needs to be explained better because it's pretty cool. Docspeleo tells me that they tell more about PK's story on the lantern tour in the cave. If you watch the signs around the area, it's about mining the bat guano and saltpeter. These were used in explosives and specifically in dynamite, hence the display in the queue.
Does anyone have the words to the music they played in the queue when the ride opened? Do they still play the music or has it gone away like the music on AP?