Also, “why did someone mail Neo a brick?”
There’s no way to tell what scenes, if any, will leave a lasting nightmarish impression, but I suggest the disappearing mouth trick and the bellybutton bug might be problematic.
Yeah, people will just react to arbitrary stuff in movies. When I was a kid, I just could not do ET. Now, I was a bit of a nervous kid in general, couldn’t handle campfire stories or anything. But I couldn’t even get through the first hour of ET without turning it off.
A friend of mine couldn’t handle the giant fluffy adorable dragon dog in The Neverending Story, and she was pretty brave.
I think another person was freaked the hell out by the movie AI, which I guess was at least PG-13 (we would’ve been around 11 when it came out).
I’ve seen it happen to adults too.
Seems like Alessan’s wife just happened on one of those scenarios with the Matrix. It seems very unlikely that this will happen to the kid as well (unless she projects the anxiety on him by overreacting).
Yes, and of course there’s the scene where his mouth gets sealed (by his own skin) and then they let a tentacled robot work its way into his navel.
I remember the scenes when he wakes up being a bit intense.
Also, for your wife: the movie proved itself not to be real when it talked about your residual self image, which would mean you’d look like you think you look. At least, that was enough for me at the time. Of course, the sequels gave you a lot more to work with, like the fact that the Matrix was all just one big city.
At 10, I would be more worried about the violence (I mean, Neo does slaughter like 20 military dudes in the lobby) than the horror aspects.
But speaking of horror, it’s not the “nothing is real” that would worry me, it’s the “machines are going to stick tubes in my body and stuff me in a bowl of snot” scene that would get me.
I generally think kids will get adult stuff much sooner than adults give them credit for (mainly because I was a kid that got stuff much faster than adults do), but my three year old refuses to watch Jake and the Neverland Pirates anymore because the last episode had the good witch accidentally being turned the bad witch and that scene scared him so much he ran from the room screaming and crying. (Of course, Jake and crew turn the bad witch back into the good witch at the end of the episode, but he refuses to watch the end because the bad witch will be there).
So, as a father, I’d say your kid is probably fine but may surprise you. As a husband, I wouldn’t want this to be something I’d fight over with my wife 
In general, I wouldn’t think The Matrix would be particularly scary. I can understand that the existential aspects of the film could be frightening to some people, but I also think that, in general, a lot of the themes, as browbeaten as they are, would still go over the heads of most 10-year-olds. Looking back at films that scared me when I was about that age, it wasn’t because of the philosophical implications, it was because of the visual imagery in the film. I’d personally be more concerned about the interrogation, sentinels, or the awakening scenes than the existential terror.
Ultimately, though, I think it depends on the kid. It’s not about how I or someone else may have responded to it, but more how you think he would. If your wife’s concern is about the philosophical aspects, how has he reacted to films with similar themes? For instance, has he seen The Truman Show? They both cover that particular idea that the world isn’t what you think it is, but The Truman Show doesn’t have the shocking second act reveal of it.
Personally, I’d think as long as you think your son can handle the themes and action, The Matrix is such an influential film on modern cinema, that I think it’s important to see young. Ultimately, I think the idea that the world may not be real or may not be what we think it is is something that most kids by the age of 10 have considered. After all, kids spend a lot of time fantasizing, so I think they’re less likely to be frightened by the idea.
I’ve been trying to think of older instances of “what we think is the real world is not the real real world.” There’s the Alice story, Through the Looking Glass, where everyone is actually only the White King’s dream, but that only takes up a few pages.
Chuang Chou’s claim not to know if he was a butterfly dreaming of being a man is estimated to be from about 300 BC give or take a couple of centuries.
Movies and TV shows that show everything to be a dream at the end are usually less unpleasant than The Matrix, just because everyone wakes up to their old life, usually, rather than to imprisonment. I’m not going to touch TV Tropes right now, but there has to be a huge list of those.
Maybe Alessan could discuss the list with his wife, though. I imagine she’s watched other movies with the same theme that didn’t happen to frighten her.
“Inception” certainly touches on the possibility that our world isn’t the real world. But it is probably easier to handle than The Matrix.
I was 11 or 12 when I first saw the Matrix, and the mouth and the bug were the scary things. Existential horror I was already over by that point- way too many shows use the “is this real or a delusion?” trope for it to be scary.