Fallout 3 seems to perpetuate the misconception that a mushroom cloud is directly related to a nuclear explosion. But that's simply the way heated gas moves; even a smaller explosion produces a "mushroom cloud" effect, it's just briefer and less prominent than with a nuclear explosion.
Anyone else think about this?

No.

Of all the extreme inconsistencies in this game, I'd say this is right with Virgina looking like Southern California.

Yeah ok, but what exactly is your point ?

Nuclear explosions produce great mushroom clouds as they produce the most heat of all explosions.
Therefore they cause the strongest reaction with the surrounding atmosphere.

It's probably about Fatman's minature mushroom clouds.

Well, it may be that such a small nuke like the Fatman would not produce such a typically formed cloud right away like shown in F3 but it would definitely produce one.

Here is a video of a test shot of the "Little Feller 1" mini nuke. It had a yield of only 18 tons of TNT (0.018Kt).

http://www.sonicbomb.com/modules.php?name=Content&pa=showpage&pid=56

It was the intended warhead for the famous http://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)

I agree about the mushroom clouds, but I don't really see what you're getting at...