"Captain America: Civil War" D23 trailer, exclusively unveiled for the audience at Disney's D23 Expo, has been leaked online. And, the footage features a huge spoiler for the 2016 flick.

The exclusive first-look of "Civil War" was unveiled at this year's D23 expo and Disney/Marvel Studios had decided not to release the trailer officially just as yet. But somehow, various gif images and screenshots of the trailer were mysteriously leaked online.

It looks like the fans in Asia who were disappointed that they couldn't view the D23 footage got lucky when the leaked gif images were uploaded on Imgur.

Click here to view the screenshots from D23 trailer.

The leaked footage, which was taken down later, reportedly showed the much-talked-about face-off between Crossbones and Captain America. The trailer also featured shots showing the entire Captain America and Iron Man teams.

Apart from this, the clip also shows Black Panther and Winter Soldier fighting on the side of a building. Apparently, the trailer also shows a fight between Black Widow (Iron Man's team) and Hawkeye, where Black Widow asks Hawkeye if they are still friends, to which he replies: "Depends on how hard you hit me."

If the leaked information is true, then Marvel should now release the trailer officially.

Meanwhile, there has been a huge buzz about the revealed Iron Man and Captain America teams. We already know that Scarlet Witch, Hawkeye, Agent Sharon Carter, Falcon, Ant-Man and The Winter Soldier will be on Steve Rogers' side, and War Machine, Black Widow, Vision, Black Panther and Spider-Man will join Tony Stark in the big fight.

But, some reports suggests that both Robert Downey Jr. and Mark Ruffalo think that The Incredible Hulk may join the cast of "Captain America: Civil War". According to Kpopstarz, although this news is unconfirmed, it makes sense that Bruce Banner aka The Hulk joins in because General Thunderbolt Ross is already making an appearance.

On the other hand, there's speculation that the purple-skinned supervillain, Thanos (Josh Brolin), may appear in "Civil War", which is ahead of the release of "Avengers 3: Infinity War" in May 2018.

But, Brolin does not know whether the Mad Titan is confirmed for the cameo in "Civil War" or is it going to be "Avengers"-only. "I don't know which one I'm in. That's a Kevin Feige [Marvel Studios President] question. I know the trajectory of what they're doing, but I don't know exactly which one I'm in," Josh  Brolin said in an interview with MTV.

We will know which of these reports turn out to be true, only when "Captain America: Civil War" releases on 6 May, 2016, in the US and on 29 April, 2016, in the UK.