The men go into the building then downstairs into the bar. That room (especially with such tall ceilings) would be below the water table. There's a reason they have to bury the dead in above ground tombs.
I know it's trivial but every time I watch this movie (which I love otherwise) the underground bar just makes me crazy!
Never thought of it before, but you're right. Now it's going to bother me.
"The answers to all of life's riddles can be found in the movies."
Sort of reminds me of "The Apartment", where if you look at Jack Lemmon's flat and the way his bedroom and bath extend to the window (evidently looking down into an alley or something, it is quite clear that there is no place in that building for the apartment of his neighbors, Dr. and Mrs. Dreyfuss. I'm sure they were modest people, but living in a crawl space is a bit too modest.
Yes, first time I saw it I thought, "These film makers have never been to New Orleans".