I don't know if it counts as a reveal, but I was pretty shocked as a child at the end of ALF, where ALF pretty much gets taken away by the US Government to be dissected, probed, and experimented upon. Just seconds after his Alien race that came to pick him on Earth gets scared off my Government vans... Like 80's Astro Vans.
They must have thought it was the A-Team.
That show taught me to be skeptical of my television at an early age. And now I am rarely surprised by any plot twists or reveals that happen on television.