There's a lot of great ones. One I love is The Monsters are Due on Maple Street, where the town believes they've been invaded by aliens and start to turn on each other. Another one I think about is where there's a nuclear war scare, and one family has a bomb shelter and enough supplies for them to survive, but their neighbors didn't make one, so the neighbors start going crazy and try to break into the shelter. Then at the end, there was no nuclear attack, and the neighbors try to act like nothing happened, while the family is traumatized. To Serve Man and the one with the cafe where they think someone is an alien (I think that's Will The Real Martian Please Stand Up, been awhile) are classics. The one with a woman in a farmhouse fending off toy-sized invaders, only to find they are astronauts who think she's a giant.
Not sure if there's a spoiler tag on here for those people who haven't somehow seen the show (if they haven't, they need to stop being active and sit and watch some old TV reruns.)
Time Enough At Last makes me glad I'm near-sighted, not far-sighted.