There had been plenty of leaks about The Mandalorian's second season before it arrived on Disney+, including the returns of Ahsoka Tano (making her live-action debut) and Boba Fett.
However, something no one reported or predicted was Mark Hamill showing up as Luke Skywalker to lay waste to those Death Troopers. Keeping that secret was no easy task, and as the finale's director, Peyton Reed, explained in today's Disney Gallery: The Mandalorian episode, some tricks were needed.
"We had to keep Mark a secret and that went from creating misleads in the script [to] creating artwork that was not Luke [and] creating some temporary visual effects that were the character of Plo Koon," the filmmaker says.
Executive producer and writer Dave Filoni adds: "It's fairly well-known by deep core fans that Plo Koon is my favourite Jedi. A lot of people, if Plo Koon from the script got out would assume, 'Well, of course, cause Dave likes Plo Koon.' We had a digital Plo Koon head place on the actor in dailies so it looked like [him]."
You can actually see that fake concept art and VFX below and, honestly, it might have been pretty cool if Plo had shown up! It certainly wouldn't have had the same impact as Luke, and the making-of special takes a deep dive into the work that went into bringing Hamill back and the de-ageing process (it also reveals that the voice we heard wasn't real; it was synthesized).
The Mandalorian is expected to return sometime in 2022.