I've found two main ones.
The first level is heavily based on WAW's Junglee fighting, such as Marine Raiders going into enemy territory and coming to rescue someone and leaving.
I've also found a quote that's found in Single Player randomly, here it is.
- "Damn, thats a Russian block, er what we do know?"
- — Southern guy in a Beanie
- "Geez, I don't know, hows about you frag the basturds?"
- — Some black Sergeant who is very old
Doesn't that sound a lot like this from COD1?
- "That's a German, er, roadblock, uh, what do we do now?"
- — Elder
- "Geez, I don't know! Hows about you try shooting the basturds?"
- — Moody
Also, Bad Company travels to Southern South America and fights heavy local militia that use strange tactics that work.
^Note that in Battlefield RPGs don't swerve like shit, in Call of Duty they do, this might be one.
Now of course there's the whole Andes mission with trying to recover a downed satelite, Sweetwater calling heartbeat monitors pussie-ass, Haggard saying snowmoblies are for sissies.
Also on another note, you can see how Modern Warfare 2 has really infulenced the video game market of 2010. Also for anyone who wants to know why I don't change to Battlefield, it's because 'EVERY Infiniity Ward game has hooked onto my attention and curiosity and will not let go till the end of the game, I don't conceive to Jewish faith just because they hand out cookies, or to Catholic just because they give you free wine and beer do I? (Note:If anyone starts an arguement about this post, I will not complain)