Plot: Possibly the worst scientist in the universe shoots his son into outer space after an earthquake on his alien planet, and a few years later, Earth gets a new immigrant. He finds out he has amazing powers that include invincibility and imperviousness to gravity. He then moves to the big city to pose as a mild-mannered reporter and meets a hotshot female reporter who's smart, self-assured-and blah, blah, blah, you should really know all this.
Subsequent Development(s): Christopher Reeve fell off a horse at an equestrian show, paralyzing himself from the neck down. And Margot Kidder went batshit insane and started sleeping in strangers' yards. (To be fair, the wood pile was really comfortable.)
Why It Ruins the Movie: Because in Reeve's case, to appropriate a tagline, it makes us believe a man can't fly. Reeve's tragic accident reminds everyone that actually, no, he isn't Superman, despite how many times people at awards shows insisted he was, indeed, super-duper. In fact, one would probably guess that Reeve probably got annoyed at how often people patronized him because of his signature role, wanting to say, "Hey, I appreciate what you're trying to do here, but being brave in the face of adversity isn't the same thing as being able to lift tanks, okay?" In Kidder's case, it's simply a matter of wondering if her thought in the movie-"Can you read my mind?"-isn't just what she asks every person who passes her on the street when she isn't wearing a tinfoil helmet.
Plot: Lillo Brancato, Jr. plays Calogero "C" Anello, a sweet and impressionable, yet super-tough, young man who falls for a local black girl. His racist peers think this is unwise, and try to convince him of his error by killing him. The sweetness and innocence of C's young love, and the valuable lessons he learns about friendship with black people, helps him grow from a Bronx boy into a hairy Bronx man.
Subsequent Development: While breaking into an apartment to steal prescription drugs, Brancato and an accomplice shot and killed an off-duty New York police officer.
Why It Ruins the Movie: "C's" sweetness and innocence are watered down just a little by the fact that he's a stone-cold cop-killer. When he has to make a choice between his father and the local mob boss, or between his black girlfriend and his racist buddies, we keep waiting for him to just kill them all and take their prescription drugs, too.
Plot: Rambo takes up arms with a plucky, can-do Afghani Mujahideen insurgence force against the unstoppable Red power of the Soviet menace, solving the problem by shooting 203,449 Russian soldiers single-handedly. Take that, Russian fags! Signed, AMERICA!
Subsequent Development: On September 11, 2001, some members of the Afghani Mujahideen (currently known as the the Taliban) sort of attacked the United States in an extremely bad and unforgettable way.
Why It Ruins the Movie: Watching two hours' worth of Sly Stallone helping out a body of people who would eventually decide to fly a plane into the World Trade Center can be a little unsettling. You don't necessarily blame Rambo, whose heart's certainly in the right place here. You more just want to take him aside for a few minutes with some informative charts and newspaper clippings.