"I Forgot to Mention" is the twenty-fifth chapter of Uncharted: Golden Abyss.
Once at the top, Nate and Sully briefly begins to admire the view below them. They then hear gunshots from below, and wonders who could be shooting at who. Then, a helicopter rises up and the two duck behind cover as it flies over them. Sully states he never seen a chopper like that in Guerro's army. Nate suddenly realizes it was from Dante's army. Sully states that he thought Dante was no longer in the treasure hunt. Nate, who did not mention it earlier, states that Dante may have said something about hiring a small army.
The two proceed to climb back down, fighting more enemies along the way. When they climb down the final rope, one of the goons cut the rope, sending the two falling to the bottom. Nate lands on Sully and thanks him for breaking his fall. They must now find a way to the Temple of the Serpents.
This chapter continues on from the last one. You and Sully are still climbing the pyramid. Continue climbing until y'all reach the top. There are several guards you encounter on the way up. Defeat them through any mean necessary. Once you reach the top, watch the cutscene, and then begin the next phase, which is climbing back down. You will be faced with more goons coming in from the opposite sides of where you are climbing. Shoot them to stay alive and keep moving. Once you get to the last rope, a guard will cut the rope, sending you falling down to the bottom. The next chapter begins from there.