A cool little bit of information that was revealed in Disney Gallery: The Mandalorian was regarding the 501st Legion. This is a worldwide group of Star Wars fans who are dedicated to the construction and wearing of homemade screen-accurate replicas of Imperial Stormtrooper armor, Sith Lords, Clone Troopers, bounty hunters, and other villains from the Star Wars universe.
For years Lucasfilm has reached out to the 501st Legion and invited them to help out with publicity events such as big premieres and charity events to make the Star Wars presence pop.
Jon Favreau and Dave Filoni are both members of the group, and while they were shooting The Mandalorian, specifically the scene involving the final showdown with Moff Gideon, they realized they needed more Stormtroopers to beef up the scene.
So, Favreau and Filoni decided to call up members of the 501st Legion to appear in the scene, only they didn’t know they would be appearing in a scene for The Mandalorian! They weren’t given that information. They showed up thinking that this was going to be another publicity event! But, when arrived they learned about what was really going on and instead, they were turned into real Stormtroopers, and the homemade Stormtrooper suit became screen-used props.
How freakin’ awesome is that!? Those guys must’ve been beyond stoked to be called in by Favreau and Filoni to do this.