In The Deathly Hallows Part 2, when Harry saw Ron and Hermione before going into the forest to face Voldemort.
He was supposed to be under his Invisibility Cloak and he wasn't supposed to see anyone he knew, because if he did, he wasn't sure he would have had the strength to keep going. (Except Neville, whom he told to kill the snake. ANOTHER THING.)
Also, I don't think Hermione and Ron would have let him go alone, if they knew...
ALSO, they messed up Neville's badass scene where the sorting hat was lit on fire on his head and he was just like "******** YOU VOLDEMORT." He didn't give some stupid speech about heartfelt crap... Also, he was supposed to slay Nagini BEFORE Harry stopped feigning death. It wasn't supposed to be some drawn out stupid thing with Ron and Hermione.