Barry Allen’s time travel story in THE FLASH will establish an entirely new DC cinematic universe, but is inspired by a hit event in the series.
Inspired by the hit Flashpoint event

Inspired by the Flashpoint event, The Flash has accidentally “rewritten” the alternate timeline with countless events that have been seriously altered. As revealed from the trailer, The Flash’s mother was murdered when Barry was young, so the current brother has returned with the desire to save his mother’s life. However, Barry’s return to the past has “smashed cosmic reality”, creating a new alternate timeline.

Basically, there will be 2 timelines in The Flash that are differentiated by landmarks: Barry’s mother is dead (main timeline) and Barry’s mother is alive (alternative timeline). Both realities have two versions of The Flash, but there are other interesting characters that appear due to the multiverse disturbance he has caused.
Supergirl

According to DC’s original Flashpoint event, The Flash’s return and change of the past has greatly affected the Justice League. In it, Superman’s disappearance caused humanity to suffer. After falling to Earth, the son of Krypton was captured and imprisoned by the government, no longer seeing the light.
This was most likely inspired to build Supergirl’s plot in The Flash. In the trailer, Kara Zor-El is imprisoned, having a dilapidated appearance similar to Superman’s condition in the original story. Therefore, it is possible that she was captured by the government, as an experiment in another time line after falling to earth. In addition, Kara is also a necessary element for The Flash’s plan, the “metahuman” that the main character needs.
Variations of The Flash

When traveling back in time to prevent his mother from being murdered, The Flash of the main timeline accidentally encounters another version of himself. Both versions of Barry Allen are performed by Ezra Miller, but with different properties.
Having two versions of The Flash this time makes a lot of sense as it defines the multiverse concept that has officially taken shape in DC movies. Together, both Barry Allen teamed up to stop the army of the villain Zod, as well as find a way to return the timeline to normal.

In addition, a promo art of The Flash also unexpectedly revealed a 3rd version of The Flash, likely to be the film’s hidden villain (Reverse Flash or The Flash metamorphosed in the future of the timeline. Flashpoints).
“Batman” Keaton
Not only Superman but even Batman is a character heavily affected when The Flash returns to the past to save his mother. No longer the familiar orphan Bruce Wayne played by Ben Affleck, Batman this time comes from an extremely familiar universe played by Michael Keaton.

The fact that Michael Keaton’s version of Batman appeared was of great significance when in the past in Tim Burton’s series, the fate of the Dark Knight was still open. Therefore, The Flash is seen as the next chapter for Bat-Keaton’s journey on screen, possibly even serving as the ending of Bat-Keaton and Bat-Ben.
THE FLASH premieres on June 16, 2023 in 2D, IMAX, 4DX, ScreenX formats.