When you share your pencil with someone, you're trusting they won't return it eraser-less and ridden with chew marks. When you share a secret with someone, you're trusting they won't post about it on social media. When you share a dream, that's trust on a whole other level.
Unfortunately for the extractors in Inception, trust is hard to come by. Not only are they betrayed by one another but they're even betrayed by themselves when their subconsciouses take on a life of their own. If you've got some skeletons in the closet we suggest you clean them out before doing any dream sharing.
Inception is a movie about the futility of trust. Even with the best of intentions, our subconsciouses betray our true motives.
Betrayal is the antithesis of trust. Inception is a movie about how the lack of openness can lead to catastrophe, both in a dream world with Cobb, or in a relationship like the Fischers'.
While scapegoats come in handy for placing blame, there's unfortunately no such alternative for guilt (because Cobb could really use a guiltgoat…or whatever you would call it).
Cobb is dealing with a phenomenal amount of guilt. In his mind—and it's his mind that sets forth a lot of the action in Inception—he effectively killed his wife and brought a parentless world upon his children. Gulp.
Cobb's guilt is brought on by grief. He doesn't know how to deal with the loss of his wife and so he has decided to place the blame on himself. It's easier to hate himself than to admit that her death was out of his control.
Cobb's grief is brought on by guilt. He knows he was responsible for his wife's death. Mal will definitely be returning to him until Cobb stops running away and turns himself in.
Basically, Inception asks us if matter matters. If we change our definition of real, we can change our reality. Yeah, it's deep.
Cobb changes Mal's perception just like the extractor team messes with Fischer's perception. In the dream, Fischer's father seems very real, much like Mal can be real if Cobb lets her. "Real" is just a matter of perspective.
Like the people dreaming in Yusuf's basement, the world we think is real is the world that matters most to us: it doesn't have anything to do with physicality.
Even in the physical world, our experience is completely in our own minds. We only think it's a physical reality because of what we think we know about the things we see.
Each of us has a moral obligation to other people, and more consciousnesses make a reality more real. That's why dreams will never count as "real life."
The importance of time is pretty relative. Think about the two and a half hours you spent watching Inception: there is clearly nothing better than doing just that, so it was well-spent. How about the five hours you spent taking Buzzfeed quizzes, though? That was, um, probably less well spent.
Time for Cobb is essential because every moment that he has not spent with his kids is time lost. Luckily for him, time in the dream world moves much more slowly. We get some crazy cross-cuts of the different times moving at different speeds, emphasizing both the simultaneity of events and the importance of every second.
Inception is a race against time for Cobb, who must make amends before it's too late. The emphasis on time, and watches, and slow-mo isn't all about literal dreamtime; it's about Cobb rushing against the clock to get back to his family.
Living as an "old man filled with regret" is all about living alone. Saito's stay in Limbo is far worse than Cobb's when he had his wife. Saito's regret is unshared and the regret that Cobb is trying to avoid stems from a future without his children.