The 2000 film "The Contender" (search) featured Gary Oldman as a memorably sleazy Republican congressman. But according to the film's producer, that was not how the esteemed British actor played the role.

"He played a very interesting and complex character who happened to be a conservative in the movie," Douglas Urbanski said.

According to movie critic Michael Medved, Oldman's character was tweaked after the cameras stopped rolling.

"They were told that Gary Oldman's character would be sort of a sympathetic conservative character. A leader in the House of Representatives. And when you actually see the finished film, the character is portrayed as an absolute monster," Medved said.

This story is part of a special FOX News documentary, "Hollywood vs. America." Tune in Sunday at 9 p.m. EST to watch the special and come back to on Monday for more.

Jack Valenti (search), former Motion Picture Association of America president, chalks it all up to coincidence.

"I think most people in Hollywood are looking for the story rather than the promulgation of a political view," he contended. "I'm a great believer in Samuel Goldwyn, who used to say, 'If you wanna send a message, go to Western Union.'"

But Medved is doubtful.

"Whenever the political orientation of somebody is known in a film, there is this absolutely reliable equation from Hollywood," Medved said. "The equation is: conservative equals bad, and liberal equals good. Very liberal equals wonderful."

Medved also points to the recent remake of "The Manchurian Candidate" (search), in which the classic is updated to feature a Halliburton-style executive.

"The original film with Frank Sinatra, back in the 1960s, was all about a communist conspiracy to brainwash people. In the new ''Manchurian Candidate,' it's not communists, it's a corporation called Manchurian Global," Medved said.

"That's a great example of how Hollywood 'modernized' a film," said James Hirsen of conservative news site

"There is story after story of people in Hollywood who were able to get say a screenplay made into a movie, and lo and behold it was changed because it didn't fit the Hollywood world view," Hirsen said.

Medved stopped short of pointing to an industry-wide conspiracy.

"Most movies are absolutely non-political," he conceded. "My criticism of the entertainment industry would be that when they do send political messages, it is always, always from the left."

While critics complain that government and business are often portrayed as corrupt, Valenti says filmmakers' motives are often pragmatic.

"Keep in mind, one of the reasons why the FBI or the government or business are the villains is because everybody else has a constituency," he said. "Halliburton, I guess, is an easy target because it's not organized. It's not going to fight back."

Apparently, neither are the Nazis. Tom Clancy's blockbuster novel "The Sum of All Fears" was also tweaked so it would be Hollywood-friendly.

"Tom Clancy is a conservative. He's a conservative writer. His novels very often have very clearly conservative themes," Medved said. "In the original 'Sum of All Fears,' the way he wrote it, the bad guys are Islamofascist terrorists."

But in the big-screen version, which starred Ben Affleck, the villains were neo-Nazis.

"I don't think too many Americans are worried right now about the Nazi threat to the United States," Medved said.

Last year's "Runaway Jury," about jury tampering, also was an example of plot tampering, according to Medved.

The villains in the Dustin Hoffman and Gene Hackman film are gun makers. But in the John Grisham novel on which the movie was based, the bad guys are tobacco companies.

"The point is that when it comes to overt messages, liberals send those messages all the time and very often are praised for them," Medved said. "There are no movies in the recent past that send overt unapologetic conservative messages. Why? Because anybody who attempted to do that would be criticized [and] ostracized socially, if not commercially, in the Hollywood community."

But Valenti insists that such plot changes are meant to enhance the story, not shape the message.

"We produced about 750 movies last year. That's a lot of movies. Not all of them were good, some of them were so bad you had to subpoena people to get them to go to the theater. But for the most part they were good stories," he said.

The Early Years

In the early days of the studio system, Hollywood turned out pictures that Americans from all across the country lined up to see.

Silent movies all came out of the studio system in the 1940s and 1950s. The men who ran that system, whether from Paramount, Warner Brothers or Metro-Goldwyn-Mayer, were Jewish immigrants who came to America for a new life.

"What they were desperately seeking, from what we know now, is to assimilate, is to be Americans, and in that sense they were conservatives," said Richard Brown, a film instructor at New York University. "They took the American Dream very seriously."

The movies those pioneers turned out were celebrated around the world. In 1939, audiences flocked to "Gone With the Wind." And family-friendly fare like the "Laurel and Hardy" films ruled the box office.

Having just gotten out of a world war and a depression, Americans wanted to escape to the movies for entertainment. That relative calm was horribly disrupted by the Japanese sneak attack on Pearl Harbor, but Brown says that event only strengthened the country's resolve.

"There was an enormous unanimity in this country that whatever your politics were, once this country committed to it, you fought the war," he said.

But post-World War II conflicts did not have a similar effect. Rather, they seemed to splinter the country.

"You don't see that unanimity today. You didn't see it in the Korean War, which was a vague, non-declared war, and Vietnam was rife with problems," Brown said.

Those "problems" began showing up in films like the 1970 hit "MASH." According to Newsmax's Hirsen, the collapse of the old studio system changed the movie business forever.

"Hollywood sort of had a complete sea change, where the fundamental infrastructure shifted. And when that shift occurred ... in the 1960s and 1970s ... you can see it, in really radical departures of filmmaking. Like 'The Graduate' and 'Easy Rider' and 'Five Easy Pieces.' Films that before you would only see in an art house somewhere [were] all of a sudden hitting the mainstream," he said.

"Hollywood went from anointing 'Sound of Music' as best picture of the year in 1965 to anointing 'Midnight Cowboy' in 1969, just four years later. The only X-rated movie ever to win best picture," Medved said.

Medved points out that Julie Andrews' Maria was much more beloved by audiences than Dustin Hoffman's 'Ratso' Rizzo.

"'Sound of Music' was a gigantic, monster hit, and 'Midnight Cowboy' was emphatically not," Medved said.

In early Hollywood, performers kept their political beliefs close to the vest.

"The people that ran the studio system, their general rule was they didn't want their stars to reveal politics at all," Hirsen said.

That keep-it-to-yourself attitude also extended to the films of that era.

"There was an apolitical sense that you were an American, and that the office of president represented something, the country represented something, and that being an American was more important than anything," Hirsen said.

But in the anything-goes climate of the '60s and '70s, Hollywood stars started coming out with their political views, with some like Jane Fonda venturing into activism. For those with unpopular views, the new openness had a downside, according to producer Urbanski.

"If friends knew that you were on the right, you would lose friends over it," he said.

According to Urbanski, it is inconceivable that such a blatantly political film like "Fahrenheit 9/11" would have been made in Old Hollywood, let alone garner accolades.

"If we were in the midst of World War II, you can't imagine that Michael Moore would go and do a film about what a bad guy Roosevelt is, what a nice guy Hitler is," he said.

FOX News' John Gibson, Bill McCuddy, Joel Parks and Jason Kopp contributed to this report.

This story is part of a special FOX News documentary, "Hollywood vs. America." Tune in Sunday at 9 p.m. EST to watch the special and come back to on Monday for more.