DC Comics published a three-issue prequel comic book limited series titled The Flash: The Fastest Man Alive, written by Kenny Porter with art by Ricardo López Ortiz, Juan Ferreyra, and Jason Howard. Three issues of the comic series were released. It is set after the events of Justice League and depicts Batman training the Flash and the Flash's early days as he attempts to defeat the supervillains Girder, Tar Pit, and the Top. The first trailer for The Flash was shown during Super Bowl LVII on February 12, 2023, before playing in theaters ahead of Ant-Man and the Wasp: Quantumania. The trailer had the most engagement on social media, outpacing other trailers that were shown in the likes of Guardians of the Galaxy Vol. 3 and Transformers: Rise of the Beasts, with RelishMix reporting the trailer gained 97.4M views within a 24-hour period. Many commentators highlighted Keaton's reprisal as Batman and Calle's role as Supergirl, and also noted the de-emphasized focus on Miller's Flash following their controversies. Charles Pulliam-Moore of The Verge particularly felt that "it's the other heroes they're [the Flash] going to be allying with who are likely to steal the show", and felt that Supergirl and Keaton's Batman were being posited as the film's "World's Finest", and expressed enthusiasm for Supergirl's role in the story. Alli Rosenbloom from CNN also praised Keaton's appearance, highlighting the usage of Danny Elfman's score from Batman, while Collier Jennings from Collider felt that trailer "certainly is working to sell the image that the wait was worth it".
