hey bro 1st that is a spot so dont act like its a glitch and 2nd this has already been posted on another site. So try again and rember thats a spot glitches are errors in the game.
you can make the jump from the top of the stairs to the trailer easy, done this the first day it was released, theres also a head glitch on the opposite side of the map where you jump from the sign(with the ladders leading up) to the ramped vehicle next to the train cars