It was at that moment that Doc Kirby realized that they just found out even more about Mario's future, so they went back to the De Lorian (which now has a Mr. Fusion attached to it, for easy power source) to proceed back to the present time of 2008...
...but not before Mario asked "Wait-a Doc, if I'm-a not the one who kills you in-a da future, who does?"... to which Doc Kirby responded....