As if that wasn't enough, new trailers for all three shows and Season 3 of Arrow made their debut along with news of some new characters from the DC Universe appearing in live-action for the very first time. Here's the rundown for each series:
The big news was the announcement of Season 3's Big Bad, none other than the major Batman villain Ra's al Ghul. Liam Neeson previously appeared as live-action version of the character in the 2005 film Batman Begins, while Ra's has had a connection to Arrow through his second daughter, Nyssa al Ghul, and that he trained Malcolm Merlyn in Nanda Parbat.
In addition, we learned that Ted Grant, better known as the superhero Wildcat, will be appearing sometime during Season 3 and he'll have some interaction with Laurel Lance.
Proving that his abs are real by taking off his shirt, star Stephen Amell explained that the theme of Arrow Season 3 was "Identity" and whether he could be Oliver Queen and the Arrow. "It's Arrow, but with a little more green," he said.
Here's the new Season 3 trailer with Ra's al Ghul, which features Season 2 footage for about a minute before the new goodness...
Despite NBC's silly broadcast standards, John Constantine was confirmed as a smoker for the series, which will be worked around by showing him lighting up and putting out cigarettes but not inhaling.
The character of Papa Midnite, who previously appeared in the 2005 Constantine film, will appear during the first season and so will Jim Corrigan, better known as the supernatural superhero The Spectre. Also, the helmet of Doctor Fate, which appears in the pilot, could lead to the character being seen somewhere down the line.
Here's the new trailer for the series, which features some additional footage not seen in the pilot...
The new CW series discussed the coming of Robbie Amell as Firestorm and Wentworth Miller as Captain Cold once again, and also explained that the use of Clyde Mardon in the pilot means there's always the option to have his brother, Mark Mardon, show up as the Weather Wizard.
Star Grant Gustin said he has genuine affection for the character of Barry Allen. "He's a dork, and he's brilliant, and there's a lot of depth to him," said Gustin. "He's easy to relate to because he's so genuine."
Producer Greg Berlanti also teased the first major crossover between The Flash and Arrow, revealing episode eight of the season was "Flash vs. Arrow."
Meanwhile, executive producer Andrew Kreisberg explained that the different tones between The Flash and Arrow is intentional because "we were very conscious of not wanting to do the same show twice." Since Arrow has a "much darker quality to it," The Flash is "lighter, brighter, and a little bit blue sky."
As for the twist at the end of the pilot, Tom Cavanagh merely remarked of his character, Harrison Wells, that "Sometimes in the comic book world, people aren't what they appear to be. And this might be one of those instances."
And here's a fun new teaser promo for The Flash, showing everyone's favorite Fastest Man Alive breaking the sound barrier...
Gotham's young star David Mazouz, who plays Bruce Wayne, charmed the crowd by saying he'd like to wear the batsuit one day. "I think Batman becomes Batman when he is twenty-five, so hopefully this show will run until I'm twenty-five," Mazouz said to a big laugh.
Robin Taylor, Gotham's villainous Penguin, received a warm welcome from fans inside Hall H. "As an actor, you just want to get the best material possible," said Taylor. "When I come to set and look at what we're doing for the day, and I see what's written…I feel like I'm just stepping into something amazing."
As for upcoming characters, everyone remained mum on the subject apart from saying that they want to slowly tease villains over the course of the season.
And here's the new trailer for the series, with some rather ominous foreshadowing for Oswald Cobblepot...
Gotham premieres first on Fox on September 22nd, followed by The Flash on The CW on October 7th. One day later, Arrow returns to The CW for Season 3 on October 8th and Constantine premieres on NBC on October 24th.