And people seem to think kids can't separate fantasy and reality, which amazes me given that everyone after all have been children themselves, and many of them do have their own.
My son is four. He watches a lot of stuff I was never allowed to as a child. He acts out scenes of decapitations with swords, for example, while playing. When his mom and I occasionally gasp or ask him to tone it down because we think it's going a bit far he goes "it's only pretend" with a condescending voice, as if we must be the stupidest people around to not realise that these things are just fantasy.
But if we as much as raise our voices to each other, he gets upset, tells us off and demands an explanation and wants to know who is angry at whom and why. Once we had an argument before his bedtime, and I left the room. The following night he wanted assurances from me that we were not going to argue again before I was allowed to sit down by his bed. He also understands well enough that so much as raising a hand at someone is unacceptable to the extent that when he is really upset, he has experimented with using the threat of it to try to get a reaction out of us (e.g. sitting on the sofa and calmly saying "I am going to hit you"). None of the stuff he's seeing in movies or his cartoons etc. has ever "crossed over" to non-play/fantasy situations.
I don't worry about movies. I worry about advertising. He can tell movies are fantasy because of how it is portrayed, but advertising makes claims intended to be believed, and from what I see it's effect is far stronger. Thankfully he's learned to detest advertising, and now get upset if we watch live TV because he wants to fast forward past it...