The clothes etc. - my theory
There have been a lot of complaints about the clothes and hairdos being not early Thirties which of course is true. One can assume though that the costume and make up designers knew what they were doing. I think Michael Dunn's character gives it away. In the beginning he says that the audience might find themselves on this ship (of fools), in the end he says "You wonder what does this have to do with me?". I believe that the contemporary look (60's) was a fantastic knack as the prejudices and evil found on this ship are just as alive today, in the 60's and any given time as they were in 1933. Had the look been Thirties you would have been much more distant, as in "that's history and done and over with".
Just my five cents.