Amy, Colin and Bright's last day out together as a trio. Laughs are had, R.E.M's "Man on the Moon" is playing on the car radio, and it's just like old times again. Considering what Amy and Bright went through with Colin for the last half of the season, this is a huge deal.
Amy and Ephram confessing their feelings to each other.
Amy in the kitchen helping her mom after she's recovered from her rebellious depression phase, affirming how nice it is to be home.
The very gradual progression of Andy and Harold's relationship throughout series, from antagonistic rivals to Vitriolic Best Buds, is this in itself. It's made all the better seeing how much Harold is able to loosen up (especially around Seasons 3 and 4), when he'd previously come across as stuck up when not around his family.
Bright's speech to Hannah, telling her why he finds her beautiful (in contrast to most girls he's known who could be considered superficially hot, at best), is fantastic.