After President Truman told the General to send the UFO components and Dr. Zoidberg to Area 51 for study, one of them said that they were filming the fake moon-landing there. First of all, this implies that the U.S. Government would have held onto the footage for 22 years before releasing it. Also, Truman said, "Then invent NASA and tell them to get off their fannies!" This episode is set in 1947, but NASA wasn't created until October 1, 1958.
RESPONSE: This is a joke relating to the fact that many people believe the lunar landing was faked, and it is still widely disputed.