I think the problems of sex and violence could be averted if the OP took the film on a road show “exploitation” circuit, where nudity, sex, violence, etc., were common from the 1930s on. As long as an “educational” message was tacked on (or, in the cases of Gladiator or Titanic, claimed in a lecture by an “expert” simply due to its source material), road show distributors would probably be thrilled to have a competently-made shocker. Or the OP could do it himself, renting a field, and setting up a tent, screen, and chairs, then advertising in town with handbills.
If there was a “race film” exploitation road show circuit, Amistad or Glory might be good.
Thinking of race, it is strange to think how many modern movies deal with race in a manner that would be considered controversial by a significant portion of 1930s American moviegoers. Someone upthread mentioned Chicago, and I remember at the time the movie came out some posters here felt it was distractingly anachronistic to have a black prison matron. But in 1930 there were likely many whites who’d feel this casting choice was outright offensive.
The recent Disney movie The Princess and the Frog has a 1920s setting, was animated in 2D, is based on a fairy tale, and is rated G, but many 1930 theaters would probably refuse to show it. Some communities might object to having a black leading lady in a movie at all, but the fact that the story involves a foreign prince (of unspecified ethnicity) being considered a suitable marriage partner by both the black heroine and a white woman would be even more controversial.
Despite this a movie like The Princess and the Frog might have been very successful in some communities, but if our goal is to make as much money as possible with mainstream audiences then we’d unfortunately have to rule out most movies with non-white authority figures or interracial romances.
Dances with Wolves. The effects and setting would seem plausible. The question is… is a 1930s American audience ready for a movie where most of the white guys are bad guys and most of the Indians are good guys?
and a similar movie
The Last Samurai. This might be just about perfect, actually. Big spectacle, and no impossible effects. An exotic setting. And it’s a white guy who’s the hero of the story, helping out the noble but can’t-help-themselves strange foreigners.
The dinosaurs of Jurassic Park would really dazzle a 1930s audience. You could get around the anachronisms by setting the movie in the weird future of…1993! (Cue theremin!) (Of course, a 1930s audience may want to know why, in 1993, no one has a flying car, but what are you gonna do?)
The movie actually contains a cartoon explaining DNA technology, so that’s taken care of.
That still leaves you with two problems: graphic violence and the computer technology segments (I’m thinking particularly of the scenes where they are trying to get the power back on. These scenes assume some basic knowledge of computers.) Still, if you could get past those issues, the dinosaurs would really wow 'em!
Ooh, if this is possible, I’d like to nominate Caligula - even if there still would have been a bunch of scenes that would have to be cut altogether.
Actually, I came in this thread to mention O Brother…, but that’s been discussed already, so I’ll go for The Dark Chrystal (oh, too old, since it was made in 1982). Let’s say 1992’s Bram Stoker’s Dracula.
The Count of Cagliostro—or a number of Miyazaki’s other works, especially the older ones—would probably do fine.
You could probably even sell Star Wars, at least the non-special edition version. I don’t think any of the special effects would have been incomprehensibly impossible, at least from the audience’s point of view, just very difficult.
Heh. Now that I think about it, I wonder if it would be difficult at all to pass off a future movie to the people of the present—what, if anything, could you not explain away with “it’s CGI”? It’d practically have to be something like the character addressing a random audience member, by name, in every showing, and commenting on their appearance.
EDIT: Bah, crap. You said “last twenty years,” right in the OP. Most of those picks are out. Boy, the years really sneak up on you, don’t they?
Ehhh…the effects might be pushing it. Might. Personally, I think you could rationalize a hell of a lot away before you got to the point of “this should be impossible.”
I actually wonder who would catch on first—your average audience member, or a top special effects master? I mean, if you showed Willis O’Brien footage from the 2005 King Kong, would he think “wow, they really topped me” or “I don’t know what that is, but it’s not stop motion”?