It was hard to distinguish friendly vs enemy targets in multiplayer games. When you point a cross-hair on a target it should maybe display the target's name in red if it's an enemy and in green if it's a friendly. Neutral target names may be color-coded in yellow for instance.
This was confusing for me as well as many other players on the multiplayer server I was playing on as they were all complaining about this in the chat and via VOIP. I actually believe this leads to a lot of friendly fire and kills due to this ambiguity while most players are always trigger-happy.