I don't think the example about the zombie is good evidence for children noticing things more than adults. As he says, the kids' favourite plant was The Chomper. Why would that be their favorite plant? The only explanation I can think of is that they like the fact that it eats zombies. So it goes without saying that they would pay attention to the moment The Chomper eats the zombie and all the little details of the event.
Also, we all pay attention to different things, and ignore different things. So even though children notice a lot of things we don't, we probably notice a lot of things they don't. In fact, I'd bet that us adults could notice more things than kids, if we tried. The problem is that what we notice is biased by our expectations which have evolved over the years (for example, we've learned to ignore the zombie arm sticking out of the plant because it isn't important), whereas children look at everything with fresh eyes, which forces them to pay attention, which in turn makes them notice things we've stopped looking for long ago. So in the end, maybe kids do tend to notice things more than us, but it's just because they have yet to learn to close their eyes.
Also, we all pay attention to different things, and ignore different things. So even though children notice a lot of things we don't, we probably notice a lot of things they don't. In fact, I'd bet that us adults could notice more things than kids, if we tried. The problem is that what we notice is biased by our expectations which have evolved over the years (for example, we've learned to ignore the zombie arm sticking out of the plant because it isn't important), whereas children look at everything with fresh eyes, which forces them to pay attention, which in turn makes them notice things we've stopped looking for long ago. So in the end, maybe kids do tend to notice things more than us, but it's just because they have yet to learn to close their eyes.