Avengers Age of Ultron
Avengers Age of UltronFacebook/ Avengers: Age of Ultron

Just days before its big-screen release, "Avengers: Age of Ultron" is already battling an internet leak of its after-credits scene. What may come across as a major spoiler for the future films, this video that appeared on a brand new and totally unofficial YouTube channel on Monday, leaked the post-credits scene from the film giving a sneak-peek into a massive Avengers debut -- Spider-Man.

The scene features Peter Parker in the Spider-Man costume, wittily addressing a window cleaner while on the side of skyscraper, with Avengers Tower in the background. But Spider-Man is yet-to-be officially cast, hence raising doubts over the authenticity of the clip. However, it cannot be denied that Marvel is known to introduce key characters in their post-credits scenes — just as Thanos after the first Avengers and Scarlet Witch and Quicksilver after Captain America: The Winter Soldier.

"This is actually a great way to introduce the character to the Marvel Cinematic Universe, but makes no sense when an actor hasn't actually been cast in the role as of yet, shedding some doubt on its authenticity," states ComicBookMovie.

The website also points out that the Spidey suit looks very similar to the one used in "The Amazing Spider-Man 2", but Marvel's Kevin Feige had earlier confirmed that the latest Spider-Man's costume that has already been designed will be different from the earlier versions.

Other factors that raise questions are — we definitely know Andrew Garfield will not be reprising his role from "The Amazing Spider-Man" and that the studio is looking for someone in their teens to play the role of Peter Parker. Secondly, we also know from the Avengers 2 writer-director Joss Whedon and Marvel Studios boss Kevin Feige, that there will not be a post-credits scene attached to "Avengers: Age of Ultron". Instead, there is only a mid-credits button before the full credits roll. And this definitely doesn't look like the one.

Lastly, and most importantly — if it were real, then why hasn't Disney and Marvel been quick enough to take it down, especially pre-release? Strange isn't it?

Marvel's Avengers: Age of Ultron which releases 1 May 2015, stars Robert Downey Jr, who returns as Iron Man, Chris Evans as Captain America, Chris Hemsworth as Thor and Mark Ruffalo as The Hulk, together with Scarlett Johansson as Black Widow and Jeremy Renner as Hawkeye, and Samuel L Jackson as Nick Fury, Don Cheadle as James Rhodes/War Machine, Cobie Smulders as Agent Maria Hill and Stellan Skarsgård as Erik Selvig.