A crucial scene of a celebrated documentary turns out to be wrong.

Rewind: Tonight, HBO airs Roman Polanski: Wanted and Desired, a documentary that, according to the HBO press materials, raises "lasting questions about … the U.S. legal system." Without being exactly sympathetic to Polanski, the message of the film is clear: The courts did to him what he did to a 13-year-old girl in 1977.

Marina Zenovich's documentary was well-received at Sundance and at Cannes. But the film to be broadcast tonight differs in one key respect from the version that those audiences saw. The ending has been changed—apparently because it was wrong.

The final shot of the film that was seen at the festivals and reviewed by critics asserts that Polanski, who fled the United States in 1978, considered returning in 1998 but declined because the court seemed poised to screw him again. That shot was altered after the Los Angeles Superior Court took the step of contacting HBO's lawyers.

No one seems to take issue with the film's premise that the judge who originally presided over Polanski's case, Laurence Rittenband, was obsessed with the media and far less obsessed with honoring his word. Both prosecutor Roger Gunson and defense attorney Douglas Dalton say on the record that Rittenband reneged on agreements that could have resolved the case. Rittenband died in 1994, so he's certainly in no position to take issue with that portrayal.

But Zenovich concludes her film on an ironic note: In 1997, those two attorneys appeared before a sitting Los Angeles Superior Court judge—not named in the film—and reached an agreement that if Polanski returned to the United States, he would not be taken into custody. At the very end, the film states in white letters dramatically typed on a black background, the judge imposed one condition: The proceedings would have to be televised. The obvious implication: Here we go again, another Los Angeles judge poised to turn Polanski into media chum. Polanski, the film reports, turned the deal down.

But it doesn't seem to have happened that way.

There was a 1998 meeting with the judge, who was Larry Paul Fidler. He presided over the recent Phil Spector murder trial, and in that case, he allowed the cameras to roll. Spector's case was the first criminal trial televised in its entirety in a Los Angeles Superior Court since the O.J. Simpson case in 1995. That may be why Fidler was sensitive to the film's implication that he was another media-obsessed jurist.

But Los Angeles Superior Court spokesman Allan Parachini says Judge Fidler unequivocally denies that he imposed any such condition. "Judge Fidler made it very clear to counsel that any ultimate resolution of the Polanski matter could only occur in open court, on the record. There was no discussion about television coverage," Parachini says.

Parachini's office got in touch with HBO (as did we), and on Friday, HBO said that it was altering the documentary to reflect "new information" provided by the court. That must have been quite a scramble for something that airs tonight, especially since the allegation in question is kind of the film's punch line. HBO—which also will have to fix prints that are headed to theaters in July—did not say exactly how the revised ending will go. But presumably Fidler can relax.

Except that, inevitably, the film's premise is already well-established, since many outlets have already reported on it. A New York Times review from critic Manohla Dargis calls the film "sharply argued" before concluding: "Mr. Polanski survived the Holocaust and the murder of his wife, Sharon Tate, in 1969 by followers of Charles Manson. It was the American legal system that almost did him in."