This section contains a list of all secrets found during End of the Line - the ninth (and final) chapter of Uncharted: Lost Legacy. The train ride is rather short and contains only three items, and this is why they can be easily missed.
Note - The secrets are listed in the order of unlocking them. Stay with the listed order, as some of the wagons prohibit you from backtracking to the first areas of the train, forcing you to repeat the whole sequence.
Treasure 1/3 -United India Company Pistol
The item is found in the initial part of train ride. Instead of moving though the interior of the wagon, jump through the rightmost ledge and start climbing through the yellow railing and windows (screenshot 1) to access the roof of the wagon which contains the treasure (screenshot 2).
Treasure 2/3 - Viceroy's Penbox
The treasure is located on the other side of the locked wagon which sees you utilize the side ledges (screenshot 1). Proceed to the other side of the wagon, and turn around to discover the treasure (shown on screenshot 2)
Treasure 3/3 -United India Company Coins
The final treasure is found soon after the machine gun section. Retreat back to the train (shown on screenshot 1) and start moving through the wagons until you've reached the third one. Proceed through the leftmost ledge and pick-up the secret (shown on screenshot 2).