Junction Trick is a glitch that makes the game think you are going down a certain direction but you actually go down the other one.
This occurs when you change the direction of a junction on the last available frame.
In this video, the glitch is done on the last junction: the train went left (the correct way) but the game though it went right (the wrong way) so it makes me go back to the forest entrance.
If you do it on a junction in this forest, the direction trees won't load up anymore but you can still make your way to the exit (you'll have to guess by yourself the correct path).
This glitch has currently no uses.