Acceptable Losses starts behind a hangar identical to the one where the ACS Module was located in the level Cliffhanger. The player must sneak their way through the base, evading patrols and planting C4 charges on an attack helicopter, a fighter jet and inside a building. After planting these the player must escape to a location marked with green smoke.
On regular, it is possible to complete Acceptable Losses with the enemies alerted, but the player must sprint very quickly to escape the base, as enemies can quickly overwhelm them.
The ACS module from the campaign mission "Cliffhanger" can be found in Acceptable Losses (although it can not be picked up or interacted with) near the starting point.
One of the objectives is to plant C4 on a MiG-29, there are two guards conversing next to it. If one watches them for a moment, they will notice that they perform exactly the same movements at exactly the same time.
If a player approaches a standing guard from behind whilst prone, they can touch the guard's legs without alerting them or the guard they are talking with. If the player repeatedly moves against their legs, the guard will appear to jerk upwards momentarily.
When the player picks up an unsuppressed weapon, they will be referred to as Roach by Captain MacTavish. This is most likely due to reused audio files.
This actually marks the third instance in Modern Warfare 2 that a weapon is seen with three attachments:The AA-12 has a heartbeat sensor, suppressor and a red dot sight. The first is in the level "Cliffhanger", where the player start with a suppressed ACR with a red dot sight and a heartbeat sensor, and the second is in the level "The Only Easy Day... Was Yesterday", where the player starts with a suppressed M4A1 with a red dot and a grenade launcher (though it is labeled M4A1 SOPMOD).