As the two Flashes race around the world, the heroes of the DC Universe debate what to do about it. Wally and Barry are both moving so fast that the heroes can’t even catch up to them to ask them why they’re running, and all they can do is try to slow them down. The speeds the two heroes are reaching can be felt across the DC Universe, with Swamp Thing reporting a disturbance in The Green, Zatanna noting its effects on magic, The Atom trapped in an unstable microverse and even on New Genesis — which technically in its own dimension as part of the Multiversal structure — where the speedster god Fastbak warns Highfather of the Speed Force’s instability.
Barry and Wally are even running so fast that they race straight through a wall created by Green Lantern, smashing right through the manifestation of Hal’s willpower as if it was nothing.
Reaching their top speeds, Wally pulls ahead as he starts to merge with the Speed Force, turning into raw speed energy. Barry admits that he can’t keep up with Wally, who crosses some kind of threshold which Barry simply isn’t able to follow him through. Wally pulls ahead, proving to be the fastest speedster alive, but is stopped in his tracks as the Speed Force cracks open and spits the pair of them back out in Central City, where the Justice League quickly catches up to them and demands to know what’s going on between the pair of them.
While he may have won this particular race, an important thing to note is that Wally was driven by his need to rescue his family. This has always been a key motivator for Flashes, one intrinsically tied to their abilities. As noted by Hunter Zolomon, the only constant from one Flash to the next is how far they’ll go for their family. If it was Barry in a similar situation, and he believed the only way to save someone he loved was to run that fast straight into the Speed Force, he very well could be able to beat Wally in a race, because at the end of the day, “Who’s faster?” is a question children ask, not friends, and certainly not family.