the most common missed part of the game (and honestly one of my favorite early hints into Braden's personality) is Braden's bully story when you get a choice on whether to grab Braden's shoulders at the urinal to scare him or not. Your choice there may or may not active a side story you can check out in the cafeteria later. Lot of people miss that one so it's kinda turned into a hidden gem at this point