Before I read any of the responses, "rape" was the first thing that popped in my head. Not just violent rape, but any forced sex on a woman in general. This is why The Piano is my most hated good film of all time.
The other thing that is most offensive to me is rationalizations for hurting innocent people. Henry V, despite the director's attempt to make it an anti-war film, is really just a justification for attacking a nation that didn't attack first (at least, lately). Pleasantville is listed on my Criticker rankings as my least favorite film for this reason "Do what you like, damn the consequences (including hurting others), so you can be in color!"