Fast Enough

"Fast Enough" is the twenty-third and final episode of the first season of The Flash and the twenty-third episode overall. It aired on May 19, 2015.

Synopsis
Wells presents Barry with a life-changing choice. Dr. Martin Stein and Ronnie Raymond return to help the S.T.A.R. Labs team with this final fight.

Production
Preparation began March 19, 2015 and ran until March 27 2015. Filming began March 30, 2015 and ran until April 10, 2015.

Trivia

 * There were multiple Easter Eggs/references to DC Comics properties in this episode.
 * The helmet of the Greek God Hermes, most commonly associated with Jason Garrick, the first Flash, was seen as Eoboard Thawne entered the worm hole.
 * A glimpse of the Flash Museum is shown while Barry runs past Mach 2.
 * Barry also gets a glimpse of the future of Caitlin Snow, who reminisces Killer Frost and shoots ice out of her hands. Killer Frost's real name is Caitlin Snow following DC's New 52 Relaunch.
 * Eoboard Thawne reveals that the particle accelerator explosion affected Cisco Ramon, giving him metahuman powers related to vibrations. This is likened to his comic counterpart of Vibe, whose real name in the New 52 is also Cisco Ramon.
 * This episode marks the first time Hawkgirl is seen in on either Arrow or the Flash, not including the Legends of Tomorrow trailer.