It is lost fine. To be perfect, you should add the name of the movie to the first sentence (in written English). And you will need quotation marks around the name of a movie. I am going to watch the movie, "The Artist". This would be fine in spoken English: I am going to wacth a movie. The artist.

I am going to watch a movie called "The artist." I am going to watch THE movie, "The artist." That's how to do it properly.

Your mistake is expecting punctuation to write the sentence for you. Don't ever do this. "I am going to watch a movie. It's called 'The Artist'." (Proper sentences please.) If you want to throw in keywords without any structure, then your English will definitely sound broken. Also, I'm not sure if your misspelling of "watch" was typographical or phonetical.