The Tin Man expresses in "What Would I Do If I Could Feel" just how badly he misses his humanity, and how strongly he hopes having a heart will bring him closer to regaining it.
The 1984 revival adds a particularly heartbreaking moment to 'Home' inspired by the movie. As Dorothy hugs her friends goodbye and moves to centre-stage to continue singing, the world of Oz slowly fades into darkness around her. The last image we see of Scarecrow, Tinman, and Lion is the three of them huddled in shadows, reaching forlornly for Dorothy as if trying to call her back one last time.
The movie
Pretty much the whole movie overall. In addition to its funky creepiness, The Wiz is easily the most melancholic and moody Oz movie to date, with a huge emphasis on Dorothy struggling with her adulthood and needing to let go of her attachments in order to take the next steps into her life, especially after we see that a couple of Dorothy's relatives have gotten a baby child. When Aunt Em and the rest of the family at the Thanksgiving dinner sing "The Feeling That We Had" to express how she'll feel once Dorothy too manages to get so far in life but will always be welcome back home, Dorothy takes it as a tease and has to leave the dining room to go sing "Can I Go On?" expressing her self-doubt.
After Miss One and the Munchkins perform the upbeat "He's The Wizard" to urge Dorothy to get going in order to meet the Wizard of Oz who will help her get home, we're hit with a Mood Whiplash when the Good Witch and everyone else suddenly disappears leaving Dorothy all alone without knowing where she can find the Yellow Brick road. In the midst of the dark and deserted environment, Dorothy begins to sing "Soon As I Get Home" to try encourage herself.
"You Can't Win", sung by the Scarecrow as he's teased by the gang of crows. Despite how upbeat it sounds, the lyrics of the song are quite disheartening, in them the Scarecrow expresses his helplessness with verses such as: "You can't win, you can't break even, And you can't get out of the game" and "People keep sayin' things are gonna change, But they look just like, they're stayin' the same" which on top of establishing the Scarecrow as a Woobie, have a Reality Subtext that reflects the struggles black people had to endure at the time, and can still ring true nowadays.
"Be A Lion", sung by Dorothy to help the Lion pull himself together after almost killing himself out of shame of almost getting himself and her killed by the Poppy Girls. Counts as both a Tear Jerker and Heartwarming as the Lion regains his confidence and the Scarecrow and the Tin Man also support him by joining in to finish singing the song together, reinforcing their sense of camaraderie.
The Reveal that the Wizard of Oz is just a phony ordinary man. In a deviation from the book, the 1939 film and even the original musical this movie is based on, the Wizard is not treated like a Designated Hero who gets Easily Forgiven after gifting placebos to Dorothy's friends despite attempting to send them to their death by asking them to kill the Wicked Witch and then gets away on a hot air balloon, he's instead subjected to a more warranted reaction of shock and a sense of betrayal from Dorothy's group. Even after he pathetically explains his backstory they don't stop resenting him for what he did. Dorothy herself gets to sing "Believe in Yourself" to help her friends realize they had brains, heart and courage all along, while the Wizard spends the rest of his screentime observing them quietly alone in the dark, being an ashamed Atoner. The Wiz can still evoke sympathy when he begs Dorothy's group not to leave him alone, telling them they can even spend their time insulting him for the sake of not staying lonely and afraid of going outside. Only at the very end, after asking Dorothy to help him, she encourages him to go find his own place in the land of Oz (especially now that both Wicked Witches are gone) so that he can try figure it out on his own, which parallels her own character development of overcoming her fears of leaving home and finding her own place in the world.
Really, the last 20 minutes of the movie can be considered one long Tear Jerker with different flavors of heartbreak from the reveal of the phony Wizard, to the self-discovery of having the things they desired all along, to then being a long goodbye between Dorothy and her beloved companions that have helped her through her journey, both physical and spiritual. There's no bright spectacle or cheery songs, it's just characters standing in the darkness holding onto each other as they come to their sobering conclusion.
Scarecrow: Success, fame and fortune... they're all illusions. All there is that is real is the friendship that two can share.
Dorothy: That's beautiful... who said that?
Scarecrow: ... I did! [they hug] Oh, Dorothy! I'll think of you all the time!
Tin Man: And I will miss you every day. Even if I had to go back to that junk pile, even as Teenie's seat cushion, I wouldn't mind... because I have known real love!
Lion: [she embraces him too] Oh, Dorothy... If it hadn't been for you... I'd still be back on that pedestal. Afraid to live.
Dorothy: Me, too... Thank you. Thank you! Thank you for being my friends...
[Afterwards, her three companions along with the Wiz, all fade away into the darkness, hands longingly trying to reach her out.]
The TV special
A Kalidah exploits Dorothy's grief for losing her parents, by disguising as Dorothy's mama. Dorothy, surprised to see her mama again, doesn't ask how she ended up in Oz, and when the Kalidah claims that she needs the Silver Shoes in order to reach Dorothy again, Dorothy becomes more than willing to give them up...until the Tin Man alerts her of the Kalidah's trick.
The Scarecrow, the Tin Man, and the Cowardly Lion sadly walking offstage after Dorothy bids them farewell, then starts singing "Home" to return to her Aunt Em's farm.
