Nora and Bart West-Allen made a number of accidental changes to the timeline in The Flash season 8 episode "Impulsive Excessive Disorder."
This is part and parcel of life for a speedster in the Arrowverse, where it is all but impossible for someone to travel in time without unintended consequences.
The Flash season 7, where Nora "XS" West-Allen and Bart "Impulse" West-Allen traveled back in time from the year 2049 to stop Impulse's archenemy Godspeed from changing the timeline.
"Impulsive Excessive Disorder" answered this question, placing the two young heroes in a race against time to fix the unwanted changes brought about by their trip to 2021 with another trip to 2013.
Nora and Bart made a number of minor changes during their visit to 2013 that established several things in the status quo of The Flash season 1.
It seems likely that the trip will facilitate additional alterations to the future, particularly in regard to Bart's romancing a young physicist named Avery.
who may have a greater destiny ahead of her as part of the Flash family. Here is the rundown of every change Bart and Nora made to the Arrowverse timeline in The Flash season 8.