The caper takes place within a dream. Not just one dream either. The story moves between layers of sub-conscious as the action unfolds. Like any dream, reality can shift and yet seem perfectly normal. For example, the ambush in a downtown city street just after the caper begins is worthy of RONIN, yet suddenly there is a train tearing through the middle of the road. In a hotel corridor, gravity shifts and the combatants find themselves fighting gravity as well as each other.
This isn't a review of the movie. I'd been working on my 20mm armed civilians for Winter of 79 / GEEZERS, earlier in the the day and something brought them back to my mind as I watched the movie - the gaming potential, admittedly madcap gaming potential, just flooded me with ideas.
Think....INCEPTION: The Wargame. The context is that your scenario takes place within a dream. Within that dream, mission parameters always remain the same, but there can be a 'reality shift' at any time - friendly characters or enemies can can morph their abilities during the course of the action (card system such as IABSM or Ambush Alley), for instance gain super strength, ability to fly or defy gravity CROUCHING TIGER style. Weapons may become more or less powerful, additional allies, enemies, cover, obstructions can be spawned.
Then you can incorporate the odd 'reality morph'. The bank becomes a Samurai fortress, but still within a modern city, as if it's always been there.
Regardless of how far you want to go in changing charcaters, abilities or settings - the mission should always stay the same to provide an anchor for the game. You can introduce sub-plots such as rescuing the bank manager's daughter or saving Carmen in the office at work from terrorists led by your boss.
More cinematic and heroic rules such as WE CAN BE HEROES II are probably best to replicate the more fluid and high action style of gaming required, but even game systems such as Ambush Alley would work.