Is the above proper use and/or spelling?

I’ve seen people type “lightening bolt” on forums and always thought they were flat-out morons spelling it wrong. If you ask me, it should be “lightning bolt” – shouldn’t it?

I’m only second guessing myself because of the Gatorade commercial that ran during the Super Bowl tonight:

It might be hard to see, but at 19 seconds in (11 seconds remaining) there is some fine print at the bottom of the screen that reads:

“Gatorade, lightening bolt and G2 are trademarks of …”

So is “lightening bolt” proper use or ar we really living in a world of such lowered expectations that high profile national advertising features typos?