There's a 2-3 panel sequence during the Wally West era of The Flash (volume 2), when the Flash Family are planning to save the world or something. At the time, Wally is the only Flash who can time travel under his own power and the plan requires other speedsters use the Cosmic Treadmill to time travel as well. The catch is that the Cosmic Treadmill was destroyed in a fire or attack.
Wally solves the problem in 1-2 panels by popping into the past to pick up the Cosmic Treadmill before its destruction and bringing it back to the present (its future) to be used in their plan. The feat is accomplished completely without fanfare and done matter-of-factly as if there are absolutely no greater implications to being able to do this casually.
I can't remember the issue or context beyond that.