Since the Avengers relocated from Stark Tower in the heart of Manhattan to an upstate facility as depicted in Avengers: Age of Ultron, the headquarters has seen a surprising amount of change by this year's Avengers: Endgame.
A post on Reddit by user JOo_jo includes a visual chart that shows the evolution of the Marvel Cinematic Universe facility, from its debut in Age of Ultron to its brief appearance in Ant-Man, the following year's Captain America: Civil War and subsequent appearances in Spider-Man: Homecoming, Avengers: Infinity War and a glimpse in the Avengers: Endgame trailer.
Next to the screen caps from the films, a layout of the facility's architecture points out the most puzzling amount of differentiation, with the auxiliary facilities changing their placement between Ant-Man and Civil War. The entire orientation appears to shif by Endgame.
Given Tony Stark's constant need to upgrade and change things, perhaps he has spent millions in tweaking the Avengers' MCU headquarters over the years. Otherwise, it's just a small continuity error over the past four years of the MCU.
Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Chadwick Boseman, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film arrives on April 26.