So, the EPA is bringing Marge and the kids back to Springfield. We see them in the armoured truck. We see Homer try to rescue them at the SOP sign. Then, as far as I can remember, they’re back in the dome. How did EPA get them through the dome? did I miss something? I can’t remember, so I turn to the Dope for an answer.
They got gassed when they were in the truck or something, I think… we definitely don’t see how they got back inside, which is a fairly typical Simpsons device - just showing things getting worse without it making a terrible lot of sense. IIRC Marge opens her eyes and they’re somewhere downtowny-looking, like the park in front of City Hall, and freaks out a bit.
a WAG would be that the EPA had located some underground route and simply watched it instead of collapsing it, just in case they needed to pull some such dirty trick.
And now I can’t remember how HOMER got back inside. 
When’s the frickin’ DVD coming out, anyway?
The DVD comes out in December. Homer got back in by climbing the side of the dome (in a classic irony gag, we see him choose Super Glue over a jetpack. As for Marge and the kids, I was going to say that they got back in through the sinkhole, but the house stopped it up. I’m just going to say what Lucy Lawless (not Xena) did: any time you see something like that, a wizard did it.
I just finished watching the movie. They definitely don’t show you how it happened. Basically it’s just assumed there’s some sort of access point they have control of.
“bountiful penis.”