"The Ride of Your Life" from DC One Million #1 (DC, 1998) by Grant Morrison, Val Semeiks and Prentis Rollins
Why did an event called DC One Million take place in the 853rd century? Because that's when, theoretically, Action Comics would have hit issue #1,000,000. I suppose that's still true now that the numbering has been rebooted, right? I just don't want to do the math.