Mistakes happen all the time and every film has a couple of them, but Avengers: Endgame has a very peculiar (and kinda fun) mistake during the final battle against Thanos’ army, in which two Cull Obsidians can be seen... in the same shot. The Marvel Cinematic Universe began its run in 2008 with Iron Man, and its first arc reached its highest point with Avengers: Infinity War and Avengers: Endgame, bringing together all the current superheroes to fight Thanos and his army.
Avengers: Endgame followed the aftermath of Thanos’ snap, which wiped out half of all life in the universe, and the continued efforts of the remaining heroes to undo the snap. They eventually achieved it by going back in time to retrieve the infinity stones and “snapping” back those who vanished – but it came with a big price. Nebula from the past (2014 to be exact) transported Thanos and his army to the present day and thus the biggest battle in the MCU took place. With so many characters fighting at the same time, it’s easy to miss some details, such as the presence of two Cull Obsidians.
Some eagle-eyed fans noticed that the big battle in Avengers: Endgame features two Cull Obsidians in the same shot. This fun little mistake happens shortly after Captain America calls for the Avengers to assemble and the battle begins, with him hitting Cull Obsidian with the Mjolnir. Obsidian is then out of frame and the camera moves in a continuous shot to follow other characters in the battle, such as Valkyrie, Giant Man, and Black Panther. A few seconds later, Cull Obsidian can be seen again, this time overpowering Korg, with Drax leaping to Obsidian’s back, stabbing him repeatedly. Another mistake during the battle is linked to Ant-Man, who while in the van with Wasp, trying to get the quantum tunnel to work, can be seen fighting outside in his giant form.
Cull Obsidian (Black Dwarf in the comics) was a member of the Children of Thanos, and traveled with Ebony Maw to New York City to get the time stone from Doctor Strange. Once there, he fought against Iron Man and Spider-Man before being teleported to Antarctica by Wong (and lost an arm when trying to go back). He was killed during the Battle of Wakanda in Avengers: Infinity War by Bruce Banner when he attached the Hulkbuster’s arm to Obsidian’s body, sending him flying towards the Wakandan dome, with the arm exploding and killing him. Obsidian and the rest were brought to the present thanks to 2014 Nebula.
Although it’s not entirely crazy that Cull Obsidian could have gotten back on his feet and attacked Korg, it doesn’t seem quite likely as there was a significant distance between the spot where he was hit by Captain America (and where he landed) and where he was attacked by Drax and Korg. With a final battle as big as Avengers: Endgame's, it’s understandable that mistakes like two Cull Obsidians (and two Scott Langs) slipped in, which ended up being a fun detail and not a tragic one that changes the plot or diminishes the film.