In the bank vault, Casey injects some quick-hardening plastic into the safe deposit box's slot for the bank's master key. Seconds later, she withdraws a perfectly-formed duplicate master key. As evidenced by the type of keys used, this is what's called a warded lock. Injecting a molding liquid into the lock would not have created a key, but would simply have frozen the lock mechanism in place and leaked into all the crevices inside.
When Phelps was using the heater to remove the wire from his hands, sparks were seen and the wire was perfectly separated. In reality this would only give severe burns or if Phelps were grounded, a severe electrical shock.
When Jim throws the cleaning fluid at the heater, it bursts into flames. Tetrachloroethylene, the most commonly used cleaning fluid is non-flammable.
When Barney picks the lock on the elevator control panel, he never actually turns the lock, and you can tell that he had the door slightly open the whole time.