Think about what we see.
- We see Cobb spinning the top in a dream. It doesn't stop spinning
- In the "real world" (or what we assume is real), we see Cobb spinning the top and examining it as it does. We see the top stop spinning and fall.
- We see the top spinning as the movie fades to black
But let's look at the script again.
Cobb fumbles in his pockets, pulls out his spinning top. He
tries to set it spinning on the back edge of the sink, but it
FALLS to the floor and rolls towards the door- Saito is
there. WATCHING Cobb. He looks down at the spinning top.
What is Cobb really doing when he's watching the top?
INT. BATHROOM, WORKSHOP - CONTINUOUS
Cobb STUDIES the spin of the top as it decays, becoming more
and more ECCENTRIC...
[snip]
INT. BATHROOM, WORKSHOP - CONTINUOUS
Cobb’s spinning top WOBBLES OVER.
[snip]
Cobb GRABS it like a drowning man reaching for a lifeline.
He's studying the spin of the top. Now let's think about Arthur's weighted die. There is more to it that just the fact that it's loaded - it's weighted specifically; it will always feel a certain way and it will always behave a certain way.
What if Cobb isn't watching to wait and see if the top falls over at all, but waiting to see how it spins?
But wait! Cobb said it would never topple in a dream!
Yes, yes he did. But he was referring to Mal's totem.
COBB
This one was hers. She'd spin it in
a dream and it would never topple.
Just spin and spin...
There was some previous discussion on whether or not the top is still reliable as a totem. And this brings us back to the question of whether or not the top really is Cobb's totem at all.
Throughout the movie, other people touch the top (even if only within dreams). The one rule was to never let anyone else touch the totem so that no one could ever figure out the secret trait(s). But Cobb is just telling Ariadne - the architect - the secret trait? Now Ariadne could insert a top that always falls into the dream and Cobb would never know he was in a dream. So, that's good evidence that either the top is not the totem to begin with, OR that the fact that it never falls is a misdirection.