Tigger's completely heartbroken expression when he finds out that his "family" is really his friends in disguise and thinks that they see his family as a joke.
When Roo comes to Pooh begging him to help him find Tigger.
The Tigger Movie, a video in which Tigger discovers the implications of being "the only one": He has no family.
Tigger, after finding out that his friends disguised as his family weren't his actual family and going off to find them, says the exact words, "TTFE: Ta-ta forever!"
The worst part was near the end, when, certain that his non-existent family is coming back for him, Tigger ventures deep into the woods during a snowstorm. The sheer heartbreak on his face and in his voice as he suddenly realizes no one's there is just...
And then it just kept piling on the angst. Tigger's friends go after him in said perilous snowstorm and BEG for him to come home and out of danger. The way Tigger painfully shouts "NO" makes you feel every ounce of what both sides are experiencing in that scene.
Just after the above "NO" scene, an avalanche starts. Everyone runs for the nearest object, the tree Tigger believed to be his family tree. Tigger starts bouncing with all his might to get everyone else to safety, and as soon as he tosses up his last friend, Rabbit, he gets swept away by the avalanche. Roo then goes in to rescue him. A shock chord plays when Tigger gets attacked by the avalanche, cue lots of flinching and shocked gasps.
For that extra touch, listen carefully, who is the person giving the most shrill and horrified reaction to Tigger's supposed demise? Rabbit.
Rabbit: Are you crazy!? It's not safe out here!
Tigger: Exac-ti-cally! That's why you should all go home where it's safe! But I've got to wait here in my family tree. For my! Real!Family!
Roo's role in the story is even more heartbreaking, spending the entire movie trying to cheer up Tigger and get his idol to notice and love him like a 'big brother', though is either ignored in Tigger's obsession to find his family, or makes things worse. This hits even harder during the climax where he repeatedly attempts to just hug Tigger though is distracted or ignored each and every time, until about the final two minutes when Tigger finally accepts his friends as his real family and thus gives special notice to his "bestest little brother". Having been mostly a side character in previous Pooh features, an enormous Woobie role was a good way to start Roo's ascention as a Breakout Character, suitingly just like Tigger himself.
And then there's the end credits song, "Your Heart Will Lead You Home." In fact, the end credits period, still drawing replicating events of the story but in the style of E. H. Shepard, the original illustrator of the Winnie The Pooh novels. The same heartbreaking story with an added nostalgic tear for fans of the original A. A. Milne books.