When Sam is playing with the boy he is playing "Future Boy" who is a character he leaped into in Season 3, episode 13.
In this installment, Sam's character, the real Roberto, is never shown via mirror image, but on camera and television screens instead.
The fight scene in the opening is meant to be similar to the real-life brawl that occurred on "Geraldo" in 1988. Geraldo Rivera had his nose broken during the brawl when a chair was thrown. Roberto (Sam Beckett) gets injured by being head-butted.
At the end when Sam (as Roberto) is listing the highlights for the next day's episode, he speaks of a personal experience being abducted by aliens and being held in a white room. He's describing the experience of every person that Sam leaps into while Sam is living their life. So when Roberto comes back he will indeed have such an experience to talk about.