^Yes, the Captain America
movie did overtly mention Hitler and the Nazis, but just kept them mostly offscreen. But perhaps the source of confusion is that the animated series The Avengers: Earth's Mightiest Heroes
did avoid mentioning the Nazis at all and portrayed WWII as a battle strictly against HYDRA.
My impression is that these things are done to avoid censorship in Germany, since German law doesn't allow any Nazi imagery in children's programming, or is it in movies/TV altogether? Toy sales are also a major consideration -- nobody wants to go around selling children toys with swastikas on them.