What is the name of the movie in which the third act reveal is that the aliens are really kids kids who stole their parents space ship?

I’m pretty sure you’re thinking of Explorers, directed by Joe Dante.

http://en.wikipedia.org/wiki/Explorers_(film)

But in Explorers the kid makes the space ship.

It’s the only one I can think of where alien kids steal their parents ship, though.

Yeah, this is from Explorers:

“A bigger spaceship shows up and scoops up the aliens’ ship. Wak suggests to the boys that they are space pirates and tries to get the boys to leave quickly. Before they reach the boys’ ship, it proves to be carrying the aliens’ father and that Wak and Neek are errant children who stole one of the family cars. The father alien reprimands the alien children, visibly angry at the theft as well as the presence of the Earthlings.”
– Courtesy of Wiki.

Wow. I had forgotten about Explorers!
http://www.imdb.com/title/tt0089114/
R.I.P. River Phoenix :(

I’m pretty sure it was an episode of either “Outer Limits” or the newer “Twilight Zone” not the old black and whites.

Doesn’t it have the kids tormenting the guys and for most of the episode you assume that the kids are some sort of powerful entities or “Gods” of some sort and you don’t realize their immaturity until they are chided by the parents.

Or am I thinking of something else entirely?

Escape to Witch Mountain??

Came out in 1975
http://www.imdb.com/title/tt0072951/