From : ][CW][ : Fudge Packio --> "Tonight at 11:40 pm est or so I was playing on our main server, The map was Cross Roads, In the lower left choke point facing nf, on the 2nd floor of the stone walled structure up the stairs if you face the nf opening SQUAT and move around in the upstairs corner along the wall you no clip through it and fall behind it , you can then run through in the no clip/glitch to the very front entrence of the nf left side opening. I will show you in game if you cant find it, Nebajoth watched me in god mode from the com when I told him about it and where it was in case I forget exactly where Good luck fixin it and if its not just our server and every server that has this glitch , alert Krenzo and the dev team you can take the credit." Haha he gets off topics, but is this something everybody already knew about?
You can clip through pretty much anywhere in that map. If you can't get through slidding you can get through by bumping yourself through with a turret.