The relevant item from the IMDB trivia page is:
In later interviews, Robert Mitchum admitted that much of the script was made up as they went along.Ah, that makes sense. Also: "[Howard] Hughes also organized a screenwriting team which extensively rewrote the film and added many pages to the first script."
As you might expect from Hughes' active involvement, it's an oddball little movie. Robert Mitchum plays the hero, a gambler down on his luck, who's dragooned into a charter flight down to a remote Mexican resort. He meets a number of colorful characters, including Jane Russell as a singer with mysterious background; Vincent Price as a famous ham actor; Jim Backus, in his best Mr. Magoo voice, as a shady investment broker.
But it soon becomes clear that Mitchum is down there at the behest of Raymond Burr, playing a gangster in Italian exile, who's finagling a method to get himself back into the USA.
The movie is basically film noir, with a hefty sprinkling of screwball/slapstick comedy. That's kind of a weird mix, especially when Vincent Price organizes a ragtag army to rescue Mitchum from Burr's clutches.
Everybody's pretty good though, especially Mr. Mitchum and Ms. Russell, who have chemistry.
I think just about everyone in this 1951 movie has passed on, save for Ms. Russell. She's outspoken, and she's my kind of woman:
My father was a Republican, and he couldn't stand what Franklin Delano Roosevelt was doing to the country. I always say I'm a mean-spirited narrow-minded right-wing, conservative Christian ... I start out with that, and if you don't like it, you can lump it. I am not politically correct.They really don't make 'em like that any more.