The Walking Dead: The Final Season

Act 3.
while in the cell with violet/louis interact with the scratches on the wall next to the door.

During Act 3, you will be locked inside of a cell with Violet/Louis. Once gaining control of the character, interact with the scratches on the wooden panels near the doors to make a comment about them and unlock the achievement. The following missable achievement can be seen in the video below at 12:11:

Full Achievement Walk-through for The Walking Dead: The Final Season Episode 3.

Obviously this will contain spoilers, but I have tried to limit this solely to the requirements to unlock the achievements

I would recommend making backups saves during the game just in case you miss something, however there are no multiple path achievements in this episode.

ACT 3
[10:06] - Tally

For text version click spoiler:

Hey guys and gals! Here is my all missable and all collectibles achievement guides in chronological order so you do not miss a thing!
Hope it helps!

Act 1
0:20: - Collectible - Pennant 1/6
0:40 - Collectible - Sketch Toy 2/6
1:00 - Achievement - Best Girl
1:30 - Achievement - As a Mouse Part
3:39 - Collectible - Horseshoe 3/6
4:05 - Collectible - Rabbits Foot 4/6
4:37 - Achievement - All Seeing
8:55 - Achievement - No Mercy
11:13 - Collectible - Wind Chimes 5/6
11:40 - Collectible - Beet Nick Toy 6/6
12:10 - Achievement - Did You Lick It?

Act 2
13:00 - Achievement - Feels Like Mine
14:53 - Achievement - NightLight
15:40 - Achievement - Personal Space
16:20 - Achievement - As A Mouse Part 2
16:52 - Achievement - Tally - When your in the jail cell with either Violet or Louis.. before interacting with the door, look to the right of it to see scratch Marks on a bit of wood.. interact with it to unlock this