Tom Laughlin's Billy Jack was slowly overshadowed/overwhelmed by Laughlin's political views. Many a war is waged on Straw, especially if it's anyone on the opposite end of Laughlin's political views. The sequels gradually swapped out much of their predecessor's face-kicking action for even more heavy-handed pontificating (with predictable results in critical/audience reception).
Most people assume The Birth of a Nation, which portrays The Klan as heroic saviors, was a tract by director D. W. Griffith. In fact, it's an adaptation of the then-popular novel The Clansman by Thomas F. Dixon, Jr, which was itself a racist author tract. Being the son of a Confederate Army colonel, Griffith may have bought into the novel's revisionist history, but he denied having any ulterior motive for making the movie. In response to criticism against Birth of a Nation, Griffith's next movie Intolerance definitely was an author tract against class-based prejudice, religious discrimination, and sexism. However, unlike Birth of a Nation, it was a huge flop.
The Blot by Lois Weber is all about attacking the sub-poverty wages given to university professors, going so far as to quote magazine editorials. The whole plot concerns the struggle of Prof. Griggs's family to survive. His daughter faints from hunger and his wife steals a chicken from the neighbors (but she puts it right back).
Bob Roberts: The entire film is one in favor of a left-wing view opposing right-wingers like Roberts, more specifically how many contemporary liberals were weak and ineffectual against the rising conservatives. In-Universe as well all of Roberts' songs have right-wing messages, which is literally the only point they have.
Richard Linklater's film version of the non-fiction book Fast Food Nation went from an exposé of the practices of the fast food restaurant industry to a two-hour rant about why people shouldn't eat meat. Despite becoming an In Name Only adaptation of the book, author Eric Schlosser (who is not a vegetarian) still endorsed the final product (which may not be that surprising when one considers that the original book is on the Literature sub-page and its ideas are not that different).
Glen or Glenda is essentially Ed Wood's exploration of gender non-conforming people like himself; he even played the title character under a pseudonym.
Gold Through the Fire: There is every indication Peter's a Protestant (likely Evangelical, based on his stated beliefs), while most Russian Christians are Orthodox-Protestants make up a very small minority. He also voices many views that are common to American Evangelicals, such as opposing separation of church and state, or evolution. Eastern Orthodox are more often supportive of it-Theodosius Dobzhansky is among the modern evolutionary synthesis's founders. Perhaps unsurprisingly, the film's creators were American Evangelicals. It's quite clearly a vehicle for these views, rather than just decrying Soviet persecution of Christians.
At the end of Charlie Chaplin's The Great Dictator, Chaplin gives a Rousing Speech where he more or less steps out of character and urges the viewers to resist the Nazis. Given that France was invaded during its production, this use of the trope is very understandable.
Steven Seagal's On Deadly Ground caps off its Green Aesop with Seagal literally lecturing the audience on environmental problems and getting a round of applause.
Persecuted is largely one long sermon on the claim that Christians are persecuted in America.
Akira Kurosawa had a very low opinion of the scandal-mongering tabloids that became very prominent in post-war Japan. The result was Scandal, a story about scummy tabloid journalists who incorrectly accuse an artist and a singer of having an affair.
Pick any film by Ishirō Honda post-1954. Even though he was a scientist at heart, he hated nuclear warfare, and his stance against them started in Godzilla (1954) where Godzilla was created as a result of reckless nuclear testing, and Godzilla being a Tragic Monster because of it. As the man who saw Hiroshima after World War II, it definitely shows.
Sherwood Pictures makes films (such as Facing the Giants and Courageous) that are specifically intended to teach about Christian morality. This makes sense, as they're produced and financed by a Baptist church.
The Atlas Shrugged film series was financed by libertarians and Objectivists to make the case for their political views. There are even cameos by libertarian and Objectivist personalities.
Seed of Chucky is this for its creator Don Mancini, an openly gay man, who used the film to describe his coming out experiences and what it felt like. The movie sets aside horror for horror-comedy and family drama. In a killer doll movie of all things.
Uwe Boll's Rampage films are a particularly weird breed of an Author Tract. Its Evil GeniusVillain Protagonist Bill Williamson is a deranged psychopath and domestic terrorist who, while Going Postal, murders innocent people by the dozens for nothing but his own self-serving reasons. However, at least once per film, he'll go on a minutes-long rant explaining that his violent actions are supposed to wake up humanity, giving a very thought-out analysis about political and economic corruption.
Frank Capra freely admitted that It's a Wonderful Life was created in part with the intention of combating a modern trend towards atheism. That hasn't stopped it from becoming a widely beloved Christmas classic which is often enjoyed by religious and secular people alike, however.
Michael Moore is open about the fact that his "documentaries" are primarily to promote his left-wing political views, having taken on American gun culture, the Bush Administration, the U.S. healthcare system, and capitalism as a whole. Two of his films were even timed to coincide with U.S. presidential elections (Fahrenheit 9/11 in 2004 and Michael Moore in Trumpland in 2016), although both failed to sway them in favor of Moore's preferred candidates.
Two or Three Things I Know About Her is nominally a Day in the Life story of a Parisian housewife who earns extra money by hooking in the afternoons, but what it really is, is Jean-Luc Godard philosophizing about language, the world, and how humans perceive reality. There are many long shots, with the camera still and focused on a single object, while Godard in voiceover says stuff like this:
"Since social relations are always ambiguous, since my thoughts divide as much as unite, and my words unite by what they express and isolate by what they omit, since a wide gulf separates my subjective certainty of myself from the objective truth others have of me, since I constantly end up guilty, even though I feel innocent, since every event changes my daily life, since I always fail to communicate, to understand, to love and be loved, and every failure deepens my solitude, since—since—since I cannot escape the objectivity crushing me nor the subjectivity expelling me, since I cannot rise to a state of being nor collapse into nothingness—I have to listen, more than ever I have to look around me at the world, my fellow creature, my brother."
In Power of the Press, Samuel Fuller—who was a former journalist, and a serving soldier in the U.S. Armynote When the film was released, Fuller had already participated in the North Africa landings, and who would go on to serve in the Sicily and Normandy landings—outlines the importance of an independent and impartial press, and his opposition to American isolationism.
