I find the hays code itself kind of interesting, and there are things prohibited in it that you wouldn't think of. I found the full text of it here: http://www.classicmovies.org/articles/blhayscode.htm
edit: here are a few pieces of it that I found interesting or amusing:
"The use of firearms should be restricted to the essentials." - this seems oddly vague and open to interpretation
"5. White slavery shall not be treated." - I know there was a lot of racism, but this seems oddly specific.
"2. The history, institutions, prominent people and citizenry of other nations shall be represented fairly." - Again, I find it amusing how vaguely they worded this.
"Note, for example, the healthy reactions to healthful sports, like baseball, golf; the unhealthy reactions to sports like cockfighting, bullfighting, bear baiting, etc." - This seems like a remarkably enlightened example for the time, especially considering that it's in a decidedly regressive document.