plot hole
The robbery and expected hostage situation are great comedy. Now, many things can go wrong when one man attempts a bank robbery. None of them does, but that's to be expected in a comedy of this sort.
The getaway includes some great gags.
But there's really nothing to hold the two parts together logically. The perpetrators are unidentified and unidentifiable, they live in New York, and none has a criminal record involving robbery.
Surely anyone clever enough to plan this caper must realize that the hours immediately following it are the absolute worst time to try to leave the city. But it doesn't occur to the planner that the gang has no reason to try.
They could have easily held on to their apartment(s), gone about their business, and left in a few weeks, after the heat had died down. But then, of course, no movie.
I'm curious how the French original handled this.