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".
Word of God states that Humans (Homosapians) in the series actually have special powers all their own but it isn't as obvious as other species. They can interbreed with most other species, they are one of only a very select few who can us magic and manipulate mana, and they are the only species who have a form of Adaptability which makes them suited to live in various climates, terrains, and even outer dimensions with little to no effort.
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!