^ They were just a representation of the actual dream initiation boxes, just as the weapons were. Think of them as physical representation of a mental trigger. The characters weren't actually hitting the button and sending chemicals. Hitting the button representation caused the characters to believe
they were initiating a second or third dream within the main dream. The mental safes or vaults would work in the same way. But this is really all part of Nolan's ideas on reality that he was exploring. What is
real? What is just a representation? Is reality just an idea that has subjugated us?
One thing that did bug me a bit....why wasn't the gravity going all wonky on the ice level as well?
I was confused about that as well. Maybe they were in to deep for the first level to cause such a drastic change on the third. Or Cobb and his associates may have allowed things from the first level into the second level to help convince Fischer that he was in a dream.
To be honest I have no idea. That aspect of the dream level was never explained very well.