Use the detonator to collapse the Pine Creek tunnel
Once you start this quest, until finished, all enemies other than the White Legs will disappear from Zion Canyon.
You cannot fast travel once this quest begins; you have to make your way entirely on foot.
Upon beginning this quest, Waking Cloud/Follows-Chalk will leave the player as a companion. Everything in their inventory will be returned to the player, possibly causing the player to become over encumbered. Furthermore, Joshua Graham will become the player's companion, but will refuse to trade inventory items. Just drop items, they will still be there if you return.
If you do not complete every optional objective, Daniel will scold you for not doing everything you could have done.
PCXbox 360 There is a game-freezing glitch that may occur as you attempt to leave Zion through the Southern Passage after completing this mission. While walking towards the exit that will lead you back to the Mojave Wasteland, you may be approached by a random non-player character (many times a member of the Great Khans) and be handed a detonator. This will cause your HUD to disappear and your game to freeze. The only way to overcome this glitch is to restart your console.
PlayStation 3 Some Sorrows tribals may be left behind at the tunnel after the completion of this quest.
Xbox 360 The game may crash when you detonate the explosives.
Xbox 360 Walking along the river with Joshua Graham can cause him to get stuck in many places.
Xbox 360 Sometimes the optional quests will not show up in one's Pip-Boy.