In the movie, Captain America (Chris Evans) is ready to face off against Thanos’ forces when suddenly he hears Sam Wilson’s voice in his ear saying “on your left.”
Portals open up across the battlefield and we see T’Challa (Chadwick Boseman) step through along with Okoye (Danai Gurira) and Shuri (Letitia Wright) before Cap is joined by every Avenger, hero and soldier who returned by the Infinity Stones.
"We spent a lot of time in the edit room playing around with the sequencing of the portals,” directors Joe and Anthony Russo said during a Reddit AMA.
“We probably didn't lock that section of the movie until about a month before the film was in theatres.
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“We always wanted Sam [Wilson] to be the first one to communicate with Cap via his comm and Sam was last in Wakanda, so logically the first portal that would open would be the Wakandan portal,” they added.
“And the first person that would logically walk through a portal from Wakanda would be the king himself, bringing his army once again to the defense of Cap and the world.”
Black Panther will be returning in a sequel but Marvel Studios boss Kevin Feige has not confirmed an official release date yet.
Writer and director Ryan Coogler is busy penning the script and both Boseman and Gurira have confirmed they will be returning to their roles.
No plot details have been revealed though there is a rumour that Marvel comics character Namor, the Sub-Mariner could be the film’s villain, which would certainly fit with an Endgame fan theory that suggests he’s talked about it during the film.
Avengers: Endgame is available in the UK on digital download from 19 August and on disc from 2 September.