- Dawson Casting: Both done in Race Against Time, and in Alien Swarm.
- Graham Phillips (Ben) was 13, playing a 10 year old, and Haley Ramm (Gwen) was 14, also playing a 10 year old in Race Against Time.
- Also, in Alien Swarm, Alyssa Diaz (Elena) was 24 playing a 16 year old, Ryan Kelley (Ben) was 23 playing a 16 year old, and Nathan Keyes (Kevin) was 24, playing a 16 year old.
- The only actual teenager was Galadriel Stineman (Gwen), who was 18 during filming, and playing a 16 year old.
- This is played straight with the voice actors for the show, who are all fully grown adults playing teens and kids.
- God Does Not Own This World: Man of Action Studios created the original Ben 10 show. It has been repeatedly stated by them and others that they have nothing to do with the three sequels, as those shows had entirely different creative teams: Dwayne McDuffie for Alien Force and Ultimate Alien and Matt Youngberg for Omniverse. Even then, they were mostly on writing duties in regards to the original series, due to the inexperience they had with animation production at the time. They only gained full creative control upon the Continuity Reboot.
- I Knew It!:
- In the first episode Max corrects Gwen that Ben had turned into an alien instead of a monster, leading fans to think he was involved with aliens sometime in his past, as it turns out he was part of a an intergalactic law-enforcement organization called the "Plumbers".
- Some guessed that Ghostfreak would turn evil when they found out the Monster of the Week was an Ectonurite in "Ghostfreaked Out", despite some sources saying that it was a completely separate Ectonurite. When the episode aired, the truth became apparent after a nightmare detailing Ghostfreak telling Ben to let him out of the watch, and then subsequently escaping the watch after dealing with Zombozo's unemployed henchmen.
- Playing Against Type: Richard Steven Horvitz as Grey Matter. The little alien is certainly more subdued (and a heck of a lot smarter) than a few of Horvitz's other well-known roles.
- At the very end of the where the elves try to get Grandpa Max to be Santa, you'll notice that the three children who talk to the old man look familiar. Who are they? Why, none other than Konohamaru, Moegi, and Udon from Naruto!
- And "Super Alien Hero Buddy Adventures" has Sakura Haruno (from Naruto's team, minus the pink hair) near the end in the crowd.
- What Could Have Been:
- The initial pitch of the show seemed to be inspired by Dial H for Hero; Ben Tennyson's prototype transformations were more along the lines of human superheroes, rather than Starfish Aliens.
- Ben himself◊ was initially designed with Youthful Freckles and red hair.
- Gwen was initially written as a classmate who happened to be friends with Ben, but otherwise had no familial relation to him. Although unconfirmed, the most likely reason for Gwen being rewritten as a cousin was so that it would be easier to justify her being on a long road trip with Ben and Max. This is referenced via a Development Gag in the What If? episode "Goodbye and Good Riddance", where Ben and Gwen become classmates at the end of the episode in order to better combat villains that might attack their hometown.
- Cannonbolt was originally meant to be in the original set of 10 aliens, but was eventually dropped in favor of Diamondhead. His early design◊ looked more like an insect (somewhat like Ball Weevil), and he had two shells in each side of his head, along with knobs which would pop up.
- "Inferno" was considered as a name for Heatblast. Amusingly, this name was used for the Polish and French dub.
- Benwolf went through numerous designs before being finalized.
- Several designs were considered for Upchuck; two of them ended up re-used for future aliens Spitter and Articguana, and two more became villains in "Ken 10."
Trivia / Ben 10