Ok so on Ambush you can get out of the map non-oldschool.
You need two people and must be on the OpFor side.
When you spawn you turn left and theres a little incave in the wall. Tell your teamate to go prone in the corner and keep pushing forward on his analog stick.
Once you get on top of him you need to tell him to crouch and then stand up you jump out.
Now your out of the map and you can run around to your own delight.
https://www.youtube.com/watch?v=FAiYr2bONT8
(Get the bomb for extra fun.
)
Also theres a spot right round at the Marine side on the left where the target "A" is in S&D you can look through and shot people.
Have fun.