With just a few weeks left until The Flash Season 3 premiere, The CW has unveiled a new extended trailer, which shows more of the alternate universe Barry Allen created. In the Season 2 finale, Barry Allen (Grant Gustin) used the speed force to go back in time and save his dying mother. In the comics, when Barry did this, it resulted in the Flashpoint Paradox, a new alternate universe which is starkly different from his own world. If that wasn't enough, we also have a new poster with Barry Allen.

Grant Gustin first revealed that this season will center on the Flashpoint comics two months ago, where he teased on Twitter that The Flash Season 3 premiere will be called Flashpoint. The Flashpoint Paradox comics debuted in 2011, written by Geoff Johns. It is set in a world that has been drastically altered, where Barry Allen wakes up one day and realizes he has no powers, and he is also the only one that realizes how other DC Comics characters have been altered. For instance, Captain Cold has become Central City's hero, the Justice League no longer exists and it was actually Bruce Wayne who was killed when he was just a boy, instead of his parents. These comics lead into DC's New 52 reboot of their comic book lineup.

In the Season 2 finale, when Barry saved his mom, it resulted in the Flashpoint Paradox, and we learned in the sizzle reel shown at Comic-Con that the show is following the comic books in this respect. This new trailer also gives us another look at Doctor Alchemy, who will be voiced by Tobin Bell. In the DC Comics, the villain has the ability to turn elements into anything he pleases, even turning The Flash himself into water vapor at one point.

It has also been confirmed that The Flash will team up with Supergirl for a musical crossover at some point this season. Last season, Grant Gustin guest-starred in a crossover episode of Supergirl, when the show was airing on CBS. Executive producer Greg Berlanti has said that the crossover will largely feature cover songs, but there may be a few original songs thrown in the mix as well. There have been rumors that Joss Whedon will direct this episode, but that has not yet been confirmed.

Returning from last season will be Keiynan Lonsdale as Kid Flash, who is seen here, along with newcomer Tom Felton, who will play series regular Julian Dorn. It has also been confirmed that filmmaker Kevin Smith will be back to direct a Season 3 episode, following his critically-acclaimed Season 2 episode that was written by Zack Stentz. Take a look at this extended trailer and new poster for The Flash Season 3, debuting Tuesday, October 4 at 8 PM ET on The CW.