Eagle-eyed Star Wars fans would have noticed a Mandalorian helmet also sitting in the booth, similar to that worn by the iconic character Bobba Fett.
Waititi later shared Favreau's post and added to the intrigue by commenting: "Why isn't anyone talking about that weird IRON-MANdolorian helmet."
In Star Wars mythology, both IG-88 and Bobba Fett first appear as bounty hunters in Empire Strikes Back, when they are hired by Darth Vader to track the Millennium Falcon and capture Han Solo and his crew.
Waititi's involvement as a director on The Mandalorian comes after Star Wars franchise boss Kathleen Kennedy pinpointed the 43-year-old as the perfect candidate.
"I would love for him to direct a Star Wars movie," Kennedy told Newshub during promotional duties for the 2017 film The Last Jedi in Tokyo.
"I think he has exactly the right sensibility. It was very exciting to see him step into the Marvel universe and do such an amazing job with Thor."