In his 2001 documentary, A Funny Thing Happened on the Way to the Moon, Sibrel states the Moon landings were faked. Sibrel has recycled many of his assertions from other hoax proponents, including the technical difficulty of crossing the Van Allen radiation belts and supposed anomalies in the photographs taken on the moon. Sibrel has no known expertise as either a radiation sickness specialist, or as a Photographer. Sibrel's arguments for faking the moon landings are rife with numerous logical fallacies, including Arguments from Ignorance and incredulity as well as Appeal to probability. The film features Sibrel-edited footage which he states was accidentally sent to him from NASA. According to Sibrel, was evidence from that film shows that the Apollo 11 astronauts were staging shots of the Earth to make it appear that the spacecraft was en route to the Moon when it was actually, according to Sibrel, still in low Earth orbit.

Sibrel confronted several Apollo astronauts, who did not respond positively when they realized that they are being challenged on their accredited achievement of landing and walking on the Moon. The most infamous incident involved Apollo 11 crew member Buzz Aldrin. According to Aldrin, he was lured to a Beverly Hills, California, hotel on September 9, 2002, under the pretext of an interview on space for a Japanese children's television show. As he was leaving the hotel, Sibrel was there requesting that he swear an oath on a Bible that he had walked on the Moon.

In July 2009, Sibrel, who worked as a Nashville taxicab driver, was charged with vandalism when he jumped up and down on the hood of a car owned by a woman with whom he was having a parking dispute. Court documents show he was arrested after the driver refused to pull out of a parking space he wanted. The arresting officer wrote, "A few moments later the parking space in front of the victim opened up and [Sibrel] drove into it and parked." Sibrel "then walked up to the victim's car and jumped onto the hood, and then jumped up and down several times." The report says he caused about US$1,400 worth of damage, after which Sibrel pleaded guilty to vandalism and was placed on probation.

Before this incident, Sibrel had interviewed Aldrin in a hotel room, as shown in Sibrel's film Astronauts Gone Wild. During the interview, after Sibrel confronted Aldrin with a videotape containing, according to Sibrel, newly discovered footage from the Apollo 11 mission, Aldrin replied: "Well, you’re talking to the wrong guy! Why don’t you talk to the administrator at NASA? We were passengers, we're guys going on a FLIGHT."