Just how true does a historical movie have to be?

UNDATED (WHDH) -- Heading into Oscar weekend, there's been a new fuss raised over an old question about the movie business: with three best picture contenders based on true stories - 'Lincoln,' 'Argo,' and 'Zero Dark 30' - just how true does a movie have to be?

In "Argo," the story of six Americans saved by a daring rescue during the Iran hostage crisis, there's a tense airport chase scene at the end that never happened.

"To make an exciting and entertaining film you have to stretch the truth. You have to dramatize things a little bit, "that's just the way movie-making is,” said Dave Karger, Fandango chief correspondent.

One critic called it 'artistic license.’

But "Zero Dark 30," the stunning procedural about the killing of Osama bin Laden, began with a torture scene even the filmmakers said they never confirmed produced useful clues and in Steven Spielberg's 'Lincoln,' they got a key fact wrong: Connecticut's two Congressman did NOT vote against the 13th amendment ending slavery.

Current Connecticut Congressman Joe Courtney wrote Spielberg that "placing the State of Connecticut on the wrong side of the historic and divisive fight over slavery is a distortion of easily verifiable facts."

“Agreed,” said Turner Classic Movies host Ben Mankiewicz.

"I think if the movie is about the passage of the 13th amendment or if it's a movie about whether we're going to torture people in the United States of America, you bet their feet should be held to the fire,” said Mankiewicz.

But Oscar has celebrated dozens of films over the years that were based on true stories but that imagined characters and dialogue and whole scenes.

From "Patton" to "A Beautiful Mind" to "The King's Speech," filmmakers relied on 'artistic license' to create historical dramas - not documentaries.

If some confuse the two, that does worry historians.

"As a teacher, I find that what students know or think they know about history often comes from movies. You have to disabuse them of the misconceptions and give them a much broader context of history than Hollywood movies are capable of giving them,” said Eric Forner, a Columbia University history professor.

In the Oscar spotlight this year - three movies about significant historical events along with the story teller's age-old question: why let the facts get in the way of a good story?