Gibson, 50, drew parallels between the collapsing Mayan civilization depicted in the movie and the United States at a screening Friday at the Fantastic Fest in Austin, the Hollywood Reporter said Monday.
"The precursors to a civilization that's going under are the same, time and time again," the actor-director said after a screening of an unfinished cut of "Apocalypto," his first directorial effort since "The Passion of the Christ."
"What's human sacrifice if not sending guys off to Iraq for no reason?" he said at the festival, which is devoted to new science fiction, horror and fantasy films.
The surprise appearance was one of the first times Gibson has spoken in public since being arrested for drunk driving in June. At a screening of "Apocalypto" last week in Oklahoma, Gibson ducked the press and entered wearing a mask and wig so he wouldn't be noticed.
On Aug. 17, Gibson pleaded no contest to a charge of drunken driving in Malibu. He volunteered to do public-service announcements on the hazards of drinking and driving, and to immediately enter rehabilitation.
During the arrest early in the morning of July 28, Gibson made anti-Semitic remarks to the arresting deputy and later apologized.
"Apocalypto" is scheduled to be released Dec. 8.