As a Moments subpage, all spoilers are unmarked as per policy. You Have Been Warned.
- In the first episode, Ben learning that Gwen and Kevin are leaving of Bellwood, leaving him a loner.
- The sheer fact that with this series everyone we had come to know and love since the original show is dead. In "So Long and Thanks for All the Smoothies", the universe actually comes to an end. Everyone and everything in it dies; Ben couldn't actually save anyone. The best he could do was have the universe recreated, and even then it is not a one-to-one copy. Aside from Ben, everyone we now know are merely copies of the originals. No matter where you fall on the Ship of Theseus Paradox, its still horrifying.
- While being in the Null Void is never fun, no character got it worse there than Phil Billings. Even if he was a scummy and manipulative creep, Phil lived a tormented and lonely life in the Void, endlessly hunted by the monsters there and eventually used as a human guinea pig by Doctor Psychobos. The Nemetrix permanently mutated him with Terroranchula DNA and overwrote his human mind, leaving a pure monster with no trace of Max's old partner. Grandpa Max himself is clearly wracked with guilt over Phil's fate, admitting that even if his partner was an awful person, he didn't deserve that.
- The reason behind Feedback's lack of usage by modern day Ben. During the course of Ben's Summer, Feedback was his most favorite alien, only it starts to be seen as him starting to crave the energy rush rather than choosing any other alien, which Azmuth, Max and Gwen call him out for it, much to Ben's anger. This proves to be the Fatal Flaw for Malware to RIP Feedback out of Ben, destroying the conductoid into dust. Ben, enraged and stricken to tears, lets out his anger to give Malware a full on overload of the Omnitrix's energy, causing the corrupted galvanic mechamorph to explode. Ben won... but at the cost of losing one of his favorite aliens. And the rest is history.Ben: That's what happened to Feedback. And it was all my fault. Happy now?
Rook: I am sorry, Ben. I did not realize…
Ben: Just forget it, alright? I wish I could…- This event was so traumatic for Ben it stopped him from telling it to Rook, who he considers a good partner and best friend.Ben: Ask me anything. I'm an open book.
Rook: Tell me about Feedback.
Ben: (eyes widen in shock before he suddenly grows serious, looking away) That book's closed…
- This event was so traumatic for Ben it stopped him from telling it to Rook, who he considers a good partner and best friend.
- Malware himself is subject to a piece of retroactive heartbreak. His entire character revolves around his anger over Azmuth's seeming lack of care and slow work on curing him, leading to eventual disaster and Ben having the Omnitrix removed. Cut to Alien Force and when Ben gets his hands on the updated Omnitrix it's revealed to have integrated a DNA Repair function. Azmuth never stopped working on Malware's cure, even if Malware himself would never be able to receive it.
- In "Store 23", Ben 23 snapping and finally admitting he does miss his Dimension's Grandpa Max. He acts like a rich show-off, but it’s actually his way of trying to fill the void with fortune and fame after the death of his grandfather before he got the Omnitrix.Ben 23: I... still miss Grandpa Max.
- In a bittersweet way, the final scene of the show with Ben declaring "We're going on a road trip!" as the view zooms out to the galaxies surrounding Earth. This was the last ever episode before the 2016 reboot and seeing Ben's journey come full-circle can definitely leave some viewers misty eyed.
