Warning: Spoilers ahead for The Flash season 8, episode 6.
Booster Gold might have changed the timeline and set up a cameo in The Flash season 8. Following the conclusion of “Armageddon,” the five-episode special event that saw the Scarlet Speedster facing off against Reverse-Flash, the Arrowverse series changed gears to focus on Bart and Nora, Barry and Iris’ children from the future.
Booster Gold (Donald Faison) made his Arrowverse debut in the Legends of Tomorrow season 7 finale. Booster Gold (aka, Mike) was tasked by the time police to become a fixer of a fixed point during World War I — he had to ensure nothing was changed where he was stationed in 1916 — but he ended up stealing the Legends’ Waverider before being arrested by the time police for excessive crimes against the timeline. During The Flash season 8's episode 6, called “Impulsive Excessive Disorder,” Booster Gold appears on the front page of a publication that reveals he was “thanked during White House visit” as Bart and Nora are scrolling through headlines to figure out what about the past changed so they can fix the timeline.
While Bart and Nora assume they are the ones who messed up by going back to help their parents fight Godspeed, which led to Jay Garrick being alive in 2049, it’s possible Booster Gold was the one behind the timeline tampering. In just one episode of Legends of Tomorrow, Booster Gold revealed he had a bit of an ego and was somewhat negligent with time travel. In the comics, the character enjoys setting up heroic saves that draw a lot of attention. He could have managed to escape the time police and gone back to 2032. Whatever he did earned him enough publicity to be thanked by the U.S. president and it’s possible this isn’t the first change he’s made to the timeline — several small alterations could have led to Joe West being shot in 2013. This could especially be true considering Barry confirmed there were no changes made to the future right before Bart and Nora headed back to 2049.
Whatever the case may be, it seems fans haven’t seen the last of the happy-go-lucky time traveler. Crucially, Booster Gold being included in The Flash episode that is focused on time travel (and so soon after his introduction on Legends of Tomorrow) suggests he might make a cameo appearance at some point during The Flash season 8. After all, bringing Booster Gold into the Arrowverse proved to be a long and arduous journey, so it makes sense that his appearances wouldn’t be limited to Legends of Tomorrow.
A big theme of The Flash season 8 is time and how it can shift, with the past, present, and future in flux depending on who is messing with certain and pertinent events. Reverse-Flash changed a lot of things during “Armageddon”; before that, Bart and Nora came to the past and wreaked some havoc on 2013. Now that Booster Gold is a part of the Arrowverse, there is no telling what kind of time tinkering he’s done. How that will affect The Flash season 8 remains to be seen, but the set up for Booster Gold’s eventual arrival seems to have already been embedded into the superhero series.