Since the movie isn’t out on DVD yet, I can’t include screenshots of the scene that I’ll be talking about. So, you’ll just have to watch the movie, or try to remember the scene if you already saw the movie.
When the kids were getting away in the Incredible Car, Violet stopped the car to tell Dash about her fear of becoming brainwashed just like Lucius, and possibly their parents as well. Then, it looked like Jack-Jack… teleported all of them into an alternate dimension.
As confirmed in this movie by Mr. Incredible, Jack-Jack can enter alternate dimensions.
And that car scene would probably be the first time Jack-Jack travels to another dimension with other people.
So why was that scene in the movie?
What if Jack-Jack understood the conversation between Violet and Dash, and then chose a dimension where he believed they would all escape a horrible future.
That scene seems to reinforce the idea that Jack-Jack is intelligent. He understood his dad when he was told to shoot lasers out of his eyes, he knows that he’ll most likely get a cookie when he disappears from his dad, and he can somewhat control his powers (even though he appears to be a bit clumsy with his powers).
If that’s the case, then the family would have been doomed without the existence of Jack-Jack. Jack-Jack didn’t just save the family by removing Elasti-Girl’s brainwashing goggles.