Make sure not to trigger the checkpoint with Jun mentioning heat signatures in the building next to that spot. Just hug the hill the Falcon is above. Triggering that dialog can screw it up. Also, if you don't get out of the Falcon before the checkpoint for successfully defending the Evac zone is triggered, you can't get out of it.
I was going through the cave at one point in that game and hear some one go "woah" and then see
TJ Ram killed ...
TJ Ram killed ...
TJ Ram killed ...
:lol
If the tank gets blown up, just revert to last save. I know that's kinda cheesing it, but it worked for me lol