Since this is a comic book, Superman and the Legionaires (Braniac, Blokk, Sun Boy, and Skunklad) fight for a few pages before they realize it was all a big mix-up. Being generous of spirit, Superman doesn't mock the ugly ass outfits the teen heroes from the future are wearing, and they get around to telling Superman the reason why they're here: Bad Superboy. Superman is all "WTF?" because he was never called Superboy; he began his super career as an adult and what kind of drugs are you damn kids on in the 30th Century anyway?
That is one small planet they're running on. That was my favorite era of the Legion. As much as I make fun of their outfits, I have to admit that is what the Legion should look like - a big Seventies disco future fashion show.
I'm not going to bother explaining how Byrne untangles the Legion history and fits it into the new Superman continuity - that's what Wikipedia and the fine folks at Legion Abstract are for. There was a point where I kind of gave up trying to follow the convolutions of Legion history, with all the Time Trapper and Zero Hour craziness. The Legion is simultaneously blessed and cursed with a rich, complex mythos and a huge cast. It can be rewarding for long time fans and comic history geeks, but I think the various Legion series have been largely impenetrable and forbidding to new readers. I call this devotion to the future history of the DC Universe Legionaire's Disease*, and I think it's why so many Legion series get cancelled.
OK, let's wrap this up. Superman #8 had great art, beefcake Clark Kent and his belt buckle, a hidden Metamorpho, hideous costumes, pages of continuity wonkery, Bad Superboy, and a nice big shot of the Disco Legion. Man, John Byrne was on fire during the Vegas Exile period!
*Actually, I don't. I just needed to fit a terrible joke in there.