The Top Gun actor was wearing a white shirt, with the phrase 'Don't Hate, Debate' dorbed on it, as well as several of his now trademark scarves around his neck.
Kilmer has been wearing scarves for some time now, following trachea surgery.
It said that the surgery 'reduced his voice to a rasp and rendered him short of breath'.
However, he appears to be in better health in recent months, having taken on a one-man show called Cinema Twain, in which he plays the storied American writer Mark Twain.
He also returned for the filming of Top Gun: Maverick with Tom Cruise earlier this year, the sequel to director Tony Scott's 1986 action classic.
Kilmer will reprise his role of Tom 'Iceman' Kazansky, Maverick's nemesis (and then latterly 'wing man') from the first movie.
He will appear alongside Miles Teller as trainee pilot Bradley Bradshaw, son of Maverick's co-pilot and best friend Nick 'Goose' Bradshaw, who perishes part way through the first film.
Also starring are Jennifer Connelly, Jon Hamm and Ed Harris, with a release date plotted for June 26, 2020.
Kilmer is also reportedly planning to take his on-stage portrayal of Mark Twain to the big screen, in a biopic movie about the writer and Mary Baker Eddy, the founder of the Christian Science movement.