@kdragon1010: Wrong. The arm always comes off, doesn't matter where you shoot him because it's a flashback. This is Call of Duty not Back to the Future, changing history isn't part of the game. You CAN program it so that if you shot someone in call of duty in the foot their arms would fly off even if that doesn't make sense. The game does what it was told to do.
orannis62: Try reading my post again. I said there was no mystic curving of the bullet into his arm. Emphasis on "into his arm." As in, no curving of the bullet so that it heads RIGHT FOR the arm. Yes I know there's wind, it's very obvious to anyone who's ever played the level that there's wind, they got the flag there showing you how hard it's blowing and everything. Maybe you'll understand what I meant if I reword it for you.
The bullet doesn't curve into his arm. The 'Wind' isn't a scripted event, it's a feature to mess with your aim. The wind doesn't automatically change in the last split second so that the bullet always curves into his arm. The only thing scripted here is the target's ragdoll effect. Meaning you can shoot him in the wrong arm and it'll still fly off. You can shoot him in the head and his arm will still fly off, you can shoot him in the torso and his arm will fly off, you can shoot him in his pinky finger, and his arm will still fly off.
You CAN shoot him elsewhere. The arm flys off because the programmers don't expect you to be looking so hard at exactly where you shot him. Even if you hit him in the foot the action happens so fast all you see is a blood spurt, a stumbling NPC and a seperated arm flying off. The bullet doesn't curve into his arm unless you happened to be aiming their and the wind was on your side. The wind is only there to make the shot difficult, not there as an excuse for the bullet to always bend toward the arm, since it doesn't. If that was true, all you'd have to do is pull the trigger once and you'd always hit him. The arm just always comes off no matter where you shoot him. You can probably find videos of the bullet landing elsewhere on youtube.
Maybe YOU should play the game again. So yeah. I know I'm answering this thread pretty late in the game but no. A real 'headshot' isn't possible. You can pop him in the big toe if the opportunity presents itself and his arm will still come off. There's no alternative ending or anything.