The scene where Charlie and Grandpa Joe open a Wonka bar together only to find nothing inside except the chocolate.
Charlie: You know? I bet those Golden Tickets make the chocolate taste terrible.
The (fake) fifth ticket being found. Charlie cries in his bed, his mother and grandparents not knowing he's still awake.
Grandpa Joe: The little boy's got to have something in this world to hope for. What's he got to hope for now?
The scene in Wonka's office, when Wonka tells Charlie and Grandpa Joe that they didn't win. Obviously, it's devastating to Charlie, and this in turn hurts Grandpa Joe, but Wonka's real purpose for the contest makes you wonder if he was angry because they "stole" from him, or if it was a more personal disappointment in Charlie.
In rehersals, Wilder downplayed Wonka's anger as a Tranquil Fury, and then on the first take of the blow-up wound up exploding with disgust and anger as seen in the film. He did this without telling Peter Ostrum what he was planning, and his look of fear and sadness is completely genuine. The poor kid looks like his world is falling apart.
At the beginning of the film, Charlie watching wistfully from outside the candy store as the other kids are able to gorge themselves on candy, a luxury he wants but can't have.
A meta example: Gene Wilder (the actor behind the title character of the 1971 adaptation, Willy Wonka) passed away on August 29th 2016 at the age of 83 due to complications of Alzheimer's disease.
The official statement released by his family announcing his death mentioned that Wilder had the disease since 2013, yet kept the news private until the end, as he did not want his youngest fans to worry about "poor old Mr. Wonka" and feel sad for him when they saw him in public. He couldn't bear the thought of being the cause of "one less smile in the world".
It also crosses into Heartwarming: many celebrities end up regretting their iconic film roles and would have used their condition to either lash out or just as likely get people to leave them alone. Wilder on the other hand understood the power of the role and wanted to ensure that every child and adult who saw him would be comfortable coming up and saying hello. He cared for children THAT MUCH.
The cast's tributes on Twitter also count.
Julie Dawn Cole (Veruca): "Time is a precious thing, never waste it." #genewilder :'(
Denise Nickerson (Violet): But weren't we so very fortunate to have been able to spend ANY time with such a beautiful soul, let alone 6-9 weeks!
Peter Ostrum (Charlie) described Wilder's death as losing a parent.
Paris Themmen (Mike) posted a tribute picture on Facebook of the Wonkavator flying into the sky.