The entire montage showing Johan and Anna falling in love and getting married, set to a beautiful song where Johan sings about how he's never met a duck as sweet and beautiful as her. Probably the most heartwarming montage this side of Pixar's Up, and predates it by a good 2 decades, even.
After Johan goes through hell to get the stolen egg back, he looks down to see, much to his horror, that the egg has burst open and is now empty. However, looking around, he then sees a tiny, newborn duckling, happily waddling away as a cheery instrumental version of "Zo Vrolijk" plays in the background, and realizes it's his son.
Henk then guides the duckling back to his home, cementing their future father/son relationship.
Shortly after Alfred is born, his brothers and sisters burst out of their eggs as well, and Anna lovingly feeds the rowdy bunch as Alfred takes a glance over the edge of their home into the unfamiliar world around him. Becomes pretty sad when you realize the tragedy that befalls them not long after that.
After Alfred's parents and siblings are all killed, Henk takes it upon himself to raise Alfred as his own, in memory of his departed friend, and comforts Alfred by saying that "I'm kinda like your daddy and mommy all at once now".
After a Time Skip, Alfred celebrates his first birthday with Henk and all of his friends, showing that everything did work out in the end.
Henk attempts to break into Alfred's cell to see him and comfort him. For a mole, he really cares about Alfred as if he was his own.
After Alfred is declared innocent of having stolen the king's ruby, he and the others ride the bus back home. Pikkie, the real culprit, sits solemnly all by himself as he deeply regrets getting Alfred in trouble... until Alfred sits down next to him and happily puts his hand on Pikkie's shoulder to assure him that he doesn't blame him at all.
Alfred goes to school wearing a hat and overalls similar to Henk's. Alfred declares his approval when he looks at himself in the mirror and says "Pico bello!" for the very first time.
Alfred stands up to Dolf when the latter insults his father, showing how close they've gotten in all this time.
Despite being enemies, Alfred still tries to comfort Dolf with the loss of his mother. Dolf might not be appreciative of it, but hey, points for trying.
After Alfred has a nightmare where Henk wouldn't let him into the house anymore because he'd grown too large, Henk reassures Alfred that he's just insecure about growing up and moving out into his own house.
Ollie and Snel coming to help Alfred build his new house, purely out of the goodness of their own hearts.
The son of the Arabian Nights-esque country's king comes to share in his father's worries late at night. With as little screentime as he gets, it's still a sweet little moment and shows how close the two are.
After Alfred's house is finished, all of his friends and several people from the nearby town come to celebrate, showing that Alfred is already well-liked in the local community.
Alfred's futile attempts at getting close to the female circus performer are just adorable in their awkwardness, as well as showing how he's growing up by becoming interested in the other gender. Even after he finds out she's already in love with the human trainer, however, he still risks his neck to save her from the wild human when he breaks out of his cage in the climax.
The White Queen is made of heartwarming moments, especially in her interaction with Alfred. She's just so impeccably polite and graceful that it's impossible not to like her, especially when she gratefully thanks Alfred for showing her a good time at the end of the episode.
Just the simple fact that Ollie and Pikkie remain good friends after growing up, as shown by them playing cards together.
It's just a brief moment, but hearing the White Queen and King calling each other "beloved" is enough to make you go "Awww". Even chess pieces can have meaningful relationships, it seems.
As noted in the Tearjerker page, the White Queen's final farewell as she marvels at seeing her first sunrise is absolutely heart-wrenching to watch.
Alfred and Henk share a nice little father & son moment reminiscing over Alfred's time with the Sea Scouts as they find an old photo from back then.
Captain Stoppel's interaction with his wife, Lisa, as he awkwardly gives her a bouquet of flowers, speaks volumes of how much the two care for each other.
Knowing he's about to be deposed, Dolf has a dream about making one of his passionate speeches in a stadium which is empty - except for a smiling, clapping Alfred. This explains why Dolf was so eager for them to work together: it's because on some level, under all his anger and bravado, Dolf is still the terrified little boy hoping for Alfred to save him from the well. All he really wants is friendship, if only his stubborn pride would allow him to admit it.
After Winnie's dinner date with Michael Duckson is cut short by his wife, she arrives at Alfred's house in a state of severe disenchantment. When she asks him why he left her alone, he turns his back and keeps on playing the piano - without a tape this time. All the furious energy he poured into practicing, despite her jokes and Henk's disgust, actually worked ... and all because he wanted to impress her.
Alfred: You must know how much I ... well ... (keeps playing)
Winnie: I love you too, Alfred.
(They share their First Kiss as the lights fade out.)
Tired out by mischief, the five baby storks fall asleep listening to Alfred's story, one of them on top of Alfred's head. He carries them all upstairs, somewhat awkwardly trying not to drop them, and tucks them lovingly into bed. One can easily imagine what a good father he will be.
After Winnie's heartless behavior in his nightmare, he is deeply relieved to see the real Winnie greet him with affection.
When Dolf broadcasts his ransom message to prove that he has Winnie, Alfred shouts an Anguished Declaration of Love at the TV screen. Winnie's reply? "You too." Even across the distance, she knows exactly what he is thinking.
In the very last scene, all of their friends - Henk, Paljas, Captain Stoppel, Ollie, Snel, Pikkie, King Ferdinand, Rangpang, the Baron - come together to celebrate Winnie's safe return and Alfred's birthday, forming a lovely bookend to episode 2. As the "camera" pans out to show the clog-shaped house aglow with lights, Alfred cheers "Picobello!" for the very last time.