Business Insider has a great oral history of Trading Places today, and it's filled with awesome tidbits about the classic film. Tidbits such as:
1. The movie was originally written for Gene Wilder and Richard Pryor
LANDIS: The script was developed for Gene Wilder and Richard Pryor. And when I was sent the script, Richard Pryor, unfortunately, had his accident where he burnt himself rather badly, and they sent it to me and said, 'What do you think?
2. The studio really didn't want Jamie Lee Curtis to be cast
LANDIS: She had just made ‘Halloween 2,’ for which she'd been paid I think a $1 million, and we paid her probably $70,000. When I cast her the studio went nuts. I was called into the head of the studio’s office and he said, ‘This woman's a B-movie actress,’ and I said, ‘Not after this movie!’
3. The movie totally revitalized Don Ameche's carrer
LANDIS: He hadn't made a movie in 14 years, he'd been doing dinner theater.
While we were shooting later in Philadelphia — he was so wonderful — I said, ‘Don, may I ask a question? How come you haven't worked in 14 years?’ And he said, ‘Well, nobody called!’
The great upshot of this is after Trading Places came out, the next movie he was in was ‘Cocoon,’ which he won an Oscar. He never stopped working the rest of his life — he made like 10 more movies, I worked with him twice more.
4. The commodities floor scenes were shot halfway up one of the Twin Towers
LANDIS: I also remember that the commodities market, it was in one of the towers at the World Trade Center on the 50th or 60th floor — no windows, and 3 to 4 stories high. That was very strange, to take an elevator up 50 or 60 floors, and then you thought you were underground.
5. Some people seemed to miss the moral of the story
HARRIS: Somebody came up to me recently and said it was because of ‘Trading Places’ that he’d gone into the world of finance, which is like a huge paradigm turn — that a film written as satire of that world ends up inspiring somebody to go into that world and make a lot of money. But it just shows how times change since that film was made.