Zeitgeist is a popular internet movie with three parts.
Part one is dedicated to religion, offering an initial hypothesis of its use as a mechanism for control. Additionally, it offers an explanation of a supposed similarity in the story of Jesus to various god and messiah stories throughout history.
Part two is dedicated to supposed inconsistencies in the government accounts of the 9/11 attacks in tandem with a hypothesis that it is in line with prior government manipulation to get the United States into war.
Part three is dedicated to the New World Order under the hypothesis that it's a group of "international bankers" who benefit from war. It includes parts suggesting the supposed constitutional illegality of income tax.
Much of the first part is interesting however either stretches the truth or outright lies to push its ideas as well as setup for the following two parts. Much of it tries to draw comparisons between Jesus and many other gods. There are of course some similarities, such as the claims that some deity (Mithra, Horus among many others) might have similar stories (for example some sort of Messiah figure) but then claims that most of them died on December 25th, which is incorrect. It also brings up into question the historicity of Jesus some of which are valid however they never dig real deep into this idea (probably due to the fact that due to the lack of evidence there is not much to say.) It also tries to draw several comparisons in the bible to astrology in an attempt to show that it is based on the same idea as everything else (such as Jesus the son and comparing it to other religions that have had sun worship. However they never quite mention the fact that Sun and Son only necessarily sound similar in English.) Much of it is interesting until you look deeper into it (which is how the whole movie is presented.) The rest of the two parts are presented much of the same way. Little bit of speculation or quote mining that at the surface perhaps looks like it has substance till looked into further. The Zeitgeist debunked link (as well as that sites further debunking of the 9/11 "truth" concept) has some decent info and shows many of the flaws.
Zeitgeist Debunked - Good site going through the movie and pointing out what is wrong with it.