[Off in the distance, on the horizon, is a flare. That looks suspiciously like a single firework only because Jenn couldn't find a better picture on Google Images. HDU fail me, Google Images?
But in case you're wondering where this flare came from, well, that's the mystery; it's clearly miles and miles from the castle, there's no special occasion, and no other flares appear. It's also North-West; if it were from the people on the expedition, it'd be more North-East.
What gives?]