His favorite alien is Humungousaur partially because he turned into him in the movie and because he is the strongest; his other favorite aliens are Big Chill, Ultimate Echo Echo, Terraspin, and Diamondhead.[RK 1] He is not a fan of Nanomech because he thought that he kinda stunk in the show and because he only made sense in the movie.[RK 2]
He became a Ben 10 fan during filming, as the producers showed the crew a bunch of episodes during a break.[RK 2]
One of Kelley's favorite moments as an actor was when he and Nathan Keyes were sitting in Kevin's Car on set and a school bus full of children stopped next to it and were mesmerized to see it. He and Nathan, both still in full costume, got out of the car to say hi to them which pumped up their excitement even further.[RK 1]
The jacket Kelley wore for the movie was custom-made to fit him perfectly and costed thousands to make.[RK 1] He gave it back to the studio as they told him they needed it for future films, and was told he would get it back to keep, but never received it and regrets not stealing it from set instead.[RK 2]
When he was on Teen Wolf, Froy Gutierrez (one of the other actors) recognized him for his work on Ben 10: Alien Swarm. He told Kelley that he was a huge Ben 10 fan, and he pulled out a replica Omnitrix and showed it to him.[RK 2]
Kelley was signed on to reprise his role in two follow-up movies, but due to differences between executives at Cartoon Network, the films were never put into production.[RK 2]