"100 Films Reviewed by Historians" page discussed in class:
http://blog.historians.org/resources/1316/100-films-reviewed-by-historians
Internet Movie Database
http://www.imdb.com/
History on Film - Check out the "historical background" tab to search for films about a given subject. Also, the "movie reviews" and "commentary" tabs may be helpful to read what others have already said about the film you're researching.
http://www.historyonfilm.com/
Reel History - A column on historical films in an independent British newspaper.
http://www.guardian.co.uk/film/series/reelhistory
world-history-movies.com - Searchable by era
http://www.world-history-movies.com/