In the movie Now You See Me, the Four Horsemen rob a French bank and later reveal that the robbery was all an illusion. When Thaddeus Bradley (Morgan Freeman) was explaining it I still couldn't understand how they did this trick.
This is really driving me crazy, would someone please explain it to me so I don't go insane?
If you're looking for any reasoning in that movie, you're looking for the unattainable.
To answer your question, you might recall that Morgan Freeman explained that the magicians stole the money as it was being loaded on the truck. They replaced the money with flash paper, which ignites without leaving any residue or smoke. That flash paper is what ended up in France, while the money was brought back to the magicians. This is how they made it seem as though the money disappeared. Meanwhile, the person they pulled from the crowd was dropped into an identical looking vault below the stage, and the money was siphoned out of this "stage vault" and out into the crowd.
Of course, flash paper needs an ignitor to work. Which means there had to be some ignition source in the actual vault in France; some source of heat or flame to make the flash paper ignite. That part was never explained because it's impossible to do what the movie said they did. Not to mention how they transported that much cash back to America without even being questioned.
The bank itself wasn't robbed - the truck delivering the money to the bank was hit before the money was delivered and the money was replaced with fake money made from flash paper which would later be burned to make it look like the vault was emptied overnight even though no robbery had taken place on site at the bank.
