Heartwarming Moments: Jake's "You won, daddy! You won!" It doesn't matter that Dennis really came in last, hours after the next-to-last person crossed the finish, because he finished, and in his son's eyes, that means he won.
Hollywood Pudgy: Dennis has a bit of a gut going, but his body type is hardly what comes to mind when one thinks of a fat guy. It's a side-effect of the role supposedly being written with Jack Black in mind.
Ho Yay: "Go on, you beautiful man! ...apologies, it's hard not to get caught up in all the excitement."
Moral Event Horizon: If Whit didn't cross it when he told Dennis he was going to marry Libby and move her and Jake to Chicago (something he hadn't even shared with them yet, and obviously meaning Dennis would never see them again), he did when he deliberately tripped Dennis and broke his ankle.
Moment of Awesome: Dennis, at the halfway point of the Marathon that he's been running for the last eight miles on a badly sprained, and possibly broken ankle, hits the wall, hard. He stands there, motionless except for the swaying, obviously exhausted. And then he crashes through the wall and keeps going to the finish line. Because he promised he would, damn it!