- Executive Meddling:
- Initially it was supposed to be simply an X-Men Family Crossover. But when Marvel needed a way to write off their properties into the Heroes Reborn universe, it was decided to use Onslaught as a device to get them there.
- It's been suggested by interviews in Life of Reilly that Marvel didn't want the finale of "The Clone Saga" to compete with the story, thus the reason for the final delay to the end of "The Clone Saga" was to accommodate "Onslaught".
- Mark Waid originally intended for Onslaught to be solely Xavier's dark side, but the editors overruled him on it and added the bit about Magneto's dark side influencing him.
- What Could Have Been: