Hercules in New York (1970) was the first movie Arnold was in. Here is the movie trailer for it ...
HOLY COW - that was almost 50 years ago! He definitely improved over the years with his acting! LOL
In his early years, his accent was so strong that they even had dub someone else's voice over his so people could understand him.
They did it for this movie and Conan the Barbarian (but then later did re-releases with his original voice).