Robbie Coltrane, who plays Hagrid, has gotten a mini-fan and a fruit but stuck in his Hagrid beard.
Crabbe and Gayle never actually became Death Eaters like their fathers, they only worked under Malfoy.
During the dementor attack, Dudley saw himself the way he truly was, making him realise, rather harshly, that he needed to change.
Neville Longbottom worked as on Auror before moving on as the Herbology professor at Hogwarts. He and Luna don't end up together.
In Deathly Hallows Part 2, when they all see that Harry isn’t actually dead George turns around to say “Fred” but there is no Fred. He