To easily escape or get over barriers fast, make sure you have the grappling hook. If you find yourself outnumbered or on low health and need to get out of an area quickly, run and find a corrugated steel wall or any other high barrier. Throw the hook over the top, then climb over and the game will instantly transport you to the other side . As you run away, press G to gather up the hook and delay the pursuers greatly. The majority of times, the enemy will just give up chasing you.
During the Night Flight level in multi-player mode, when you start on the helipad, there is a flag directly south of you. Enter one of the warehouses just south and very near the flag. Inside is a forklift that you can drive around.