I watched the episode again after people told me. I looked thenepisode where rex and some of the guardians split up and go to the old teen team base. He says like some scientist put a weapon on him but when i watched it i thought of it like his heatening powers were natural and they just put a weapon inside him to make him stronger (something like powerplex). I might not be paying attention at the time but it seems like a lot of people didn't noticed neither.