Want to know something about the movies? Then go to Internet Movie Data Base, or IMDB for short. This resource is one I consult regularly because I do a lot of movie and television reviews for this blog and for other clients.
In fact, I've written nearly 500 movie reviews for a private client's website though I can't tell you which one because of a Non-Disclosure Agreement.
There are a lot of movie data bases online, but I find IMDB to be a bit more comprehensive than most. No matter how obscure the movie is, they usually have casting, a synopsis, and technical details available.
Their movie synopses are posted by viewers, but, for the most part, they appear accurate though not unbiased. Sometimes, it's interesting to see what others think.
Good writing requires good research. Choose your sources carefully.