Utterly stealing John Scalzi's work (derived from someone else's idea, but a good one nonetheless) I've taken a selection of reasonably accurate but misleading SF (and related) movie synopses and removed the titles.
You get to figure out what the movies are. Or not. Answers, with more of the same kind of thing, at Scalzi's filmcritic blog.
1. A well-meaning computer's attempt to fulfill its mission runs afoul of a human crew with other plans.
2. A rambunctious alien child invites itself aboard a human cargo ship; a memorable game of hide-and-seek follows.
3. A bewildered teenage boy fends off his mother's disturbing and unnatural attraction to him.
4. Poor product design leads to trouble for a manufacturer and one exasperated policeman.
5. An interloper endangers the life of a small boy in a desperate attempt to get home.
6. A couple tries to have a good day at an amusement park and is thwarted by faulty ride management.
7. A young man seeks to discover if he can ever trust someone over 30.
8. A cop joins the immigration service and loses his sense of identity and his place in the universe.
9. An astronaut shows a civilization the errors of its prejudiced ways but discovers that the ways of his own people aren't always perfect.
10. Lax operating standards in a laboratory lead a scientist to change the way he lives his life.
(Oceans's) 11. A lonely programmer discovers he's spending more time in a massive multiplayer online game than he ever suspected.