It's not a flashback, but a kind of dream brought on by Karen's bad-alien probing, which means that Tom is able to invest his voyage home with characters from his alien-invasion present. His boys are thus their current ages, even though they seem to be just a little younger. Pope's a philosophy professor whose academic babble about a "simulacrum" is of course right on target. And in an alternate take on that same theme, Weaver's a derelict who's holding up scrawled signs with the truth.
But the heart of the story of Tom's voyage home is the tender love between him and his wife, and their concern that he may be having some sort of affair with a mysterious woman named Anne Glass whom Tom professes not to know. Anne in this dream is determined to get Tom to take a weekend jaunt with her to one of four cities in the U.S., and in a nice bend in the plot this turns out to what Karen wants to know from Tom: upon which city are the humans and good aliens planning their massive counter-attack against the bad aliens?
It was risky for Tom to go off on his own last week - setting up his capture and probing by Karen -- but gratifying to see even this distorted bit of Tom's life before the alien invasion, so we should be grateful to Karen, whose attempt to get the crucial info out of Tom unsurprisingly fails. But meanwhile, back in Charleston, the bad beings from space are having a little more luck. Lourdes is still at large, and, to make matters worse, Weaver - the real Weaver not the derelict - is suspecting Peralta as the mole, and is enlisting Pope's aid to keep her in the dark about certain crucial matters. Not a good position from which to launch our crucial attack, but a fine way to keep the pot boiling as we build up to the final episodes of the season.
And see also Falling Skies Returns ... Falling Skies 2.6: Ben's Motives ... Falling Skies Second Season Finale
And see also Falling Skies 1.1-2 ... Falling Skies 1.3 meets Puppet Masters ... Falling Skies 1.4: Drizzle ... Falling Skies 1.5: Ben ... Falling Skies 1.6: Fifth Column ... Falling Skies 1.7: The Fate of Traitors ... Falling Skies 1.8: Weaver's Story ... Falling Skies Concludes First Season