Disturbing scenes in the movies

[Nimrodel_9]

I can't recall seeing Aragorn decapitating the Mouth of Sauron... is this in the EE?

Yes, it was in the EE. I also found it rather disturbing. It makes Aragorn out to be arrogant. Others may argue that he is arrogant, but I don't think so.

I found Denethor's running jump in flames in Minas Tirith to be a little gratuitous and unecessary.

Very unnecessary. In the book, Denethor's death is gruesome, but I say that Denethor running around on fire and then jumping is worse. It's like being killed twice, in a way.