Corrected entry: Callahan had obviously been planning his revenge for a long time, and the microbots were a huge part of the revenge. But if Hiro hadn't invented the microbots, then the entire movie wouldn't have existed. So Callahan basically just was lucky that a kid invented these amazing things, that were somehow just perfect to get revenge.TheCleverGal
Corrected entry: When Hiro is showing off his Micro-Bots at the SFTT he puts the metal headband thingy on and the Micro-Bots start constructing themselves. Then when he takes it off all the Micro-Bots fall to the ground. However, near the end of the movie Callaghan is using the Micro-Bots to push Hiro and Baymax into the teleporter, without any help from the metal headband.