Fans were treated to a screening of "Justice League: The Flashpoint Paradox" during Comic-Con international

Convention goers willing to stay up late were treated to a special world premiere of Warner Bros.' newest DC Universe Animated Original Movie film, "Justice League: The Flashpoint Paradox" at Comic-Con International in San Diego. Hosted by Warner Brothers Home Video's Gary Miereanu, the evening started off with a special video from Comic-Con favorite Nathan Fillion, who reprises his role as Hal Jordan in the film.

After the film's screening, Miereanu brought out the movie's production team, including character designer Phil Bourassa, director Jay Oliva, casting director Andrea Romano, script writer Jim Krieg and producer James Tucker. Voice actors Sam Daly (Superman), Cary Elwes (Aquaman), Thomas Howell (Reverse Flash) and Justin Chambers (Flash) also appeared to talk about their parts in the film.

Krieg, Oliva and Bourassa kicked off the panel with a discussion about the movie's hybrid animation style,melding Western character design with anime-influenced direction.

"We really wanted to play with the strengths of the studio," said Bourassa. "Knowing that we were working with the brilliant studio, 4C in Japan, we decided to add these anime inflections that we felt would lend themselves to the world of 'Flashpoint.'"

"I just wanted it to look cool," Oliva quipped.

Fans of Oliva's "Young Justice" will notice several cameos in the movie as he went out of his way to incorporate some of the character designs from that show into this prject.

"He would just dump all these cameos on my desk. He knows I can't say 'no' to adding these characters, because they're all so much fun to draw," said Bourassa. "We really had a blast."

Screenplay writer Jim Krieg spent a little time explaining the process that went through adapting Geoff John's story, revealing that the story hadn't even concluded in the comics when he started, leading to working on his adaptation as issues were released.

"It was overwhelming to read it all at once and be like, 'Okay, what are you going to keep and what are you going to lose?'" recalled Krieg. "It was very challenging. You had to pick the things that just had to be there and then squeeze in as many as you could otherwise."

"The challenge was finishing it," Tucker said later, during the fan Q&A session. "You know, when we adapt these stories, a lot of times they're classics or revered, and this one hadn't been out long enough to really be that. So it was kind of a challenge for us to make it mean something to all of you."

Moving over to the voice actors, Thomas Howell (Reverse Flash) shared the joys of playing a villain.

"A great bad guy makes the good guys better," said Rowell.

One of the most notable pieces of casting is that of Sam Daly as Superman. Daly is, of course, the son of veteran voice actor Tim Daly, who has been the voice of The Man of Steel for many years.

"I was so excited just to be able to give voice to Superman," Daly said. "To keep it in the family was so exciting."

While Daly's casting fulfilled a legacy, "Grey's Anatomy" star and voice actor for The Flash, Justin Chambers, was just happy to be part of the experience.

"I was really, really grateful to do it, and Andrea was a huge help," Chambers said. "To get to work with a great cast like this is a big honor."

Also working in animation for the first time was Cary Elwes, whose performances marks the first time the King of Atlantis has been featured in a DC animated film.

"It was a total thrill. I mean, I thought that Aquaman was badass," Elwes said. "This is the first time I've seen the film, and I was as blown away as you guys."

"The characters are called Flash and Reverse Flash, so you want there to be some sort of similarity in the voices," casting director Andrew Romano told the audience. "I loved listening to it, hearing lines that took place between you two that almost sounded like the same guy, except Reverse Flash had that little extra nasty edge. They sounded almost like siblings."

Romano pointed out the two Kevins who voiced different incarnations of Batman in the film. While Kevin Conroy reprises his longstanding role as the caped crusader, but Kevin McKidd takes on the role of "Flashpoint's" Thomas Wayne version of the character.

Having put together a cast which featured a healthy mix of industry veterans and actors new to the world of animation, Romano emphasized how pleased she was with the final result.

"All of the people who have never done this before were just dreamy," Romano said.

Once the cast and crew had finished telling their stories, the panel opened up to a quick Q&A session where good questions earned attendees a script of the movie signed by the cast.

A little Two-Face cosplayer, who was visiting Comic-Con as his wish from the Make-A-Wish Foundation, asked the panel why some scenes from the movie weren't in the graphic novel and vice versa.

"When you're doing an adaptation some things you have to take out for time," Tucker answered. "I hope you liked it anyway."

"It was amazing!" said the little boy.

The next attendee reluctant to follow the previous interviewer, asked why it had taken so long for the Flash to get his own movie.

"Flash is a difficult character," Miereanu replied. "He's hard to pin down. You don't see a theatrical film on him yet, do you?

Referring to the graphic violence present in the movie, the next questioner asked if there was anything that DC's lawyers told the production crew that the absolutely couldn't do.

"Surprisingly enough, no," Tucker said. "This is exactly the movie we wanted to make."

"We just kinda had fun with it," Oliva added. "He let me do a lot that I would never do with Bruce [Timm]."

"If the story is right, there's a time to push the envelope," Tucker continued. "I think this was the time."

But while the movie doesn't shy away from graphic violence, it was noted that other forms of mature content was handled with a lighter touch.

"You sort of passed over the Aquaman/Wonder Woman love scene just a tiny bit," Howell pointed out.

For Romano, the sheer amount of action proved to be a challenge to overcome.

"For me there was so much action in this piece and so much fighting," said Romano. "There were hours and hours and hours of ADR where literally all the actors were doing was "hruh," "oof," "eughh" and screaming, which I hate to make an actor do more than once."

Asked if the DC animated movies will continue to push the same level of mature content in future releases, the answer was that projects will be looked at on an individual basis.

"Each movie is going to have its own flavor," Tucker said. "It depends on what the story source is. If we think it deserves to be treated with the kind of intense intensity that this one had. Not all of them will. ... Not every movie is going to be as nearly R-rated as this one was, quite frankly."

Coming up in 2014, Miereanu announced that the next animated film will be "Justice League: War," an adaptation of another Geoff Johns storyline, "Justice League: War." After that, in late-2014, Warner Brothers will release "Son of Batman," based on the Grant Morrison story. Another animated Batman film will be released as a companion piece to the upcoming video game, "Batman: Arkham Origins." The film, "Batman: Assault on Arkham," will tie into the new game. Miereanu didn't confirm the return of Kevin Conroy as the voice of Batman, but did note that Andrea Romano will be playing "Tatted-Up Boss Lady."