To many fans of The Simpsons, it seemed that the long-running cartoon might at last have overstepped the line in poking fun at its corporate paymasters in Fox television. During a recent episode's opening credits, which often provide a platform for the show's creators to score political points, they pictured a Fox News helicopter adorned with the slogan "Fox News: Not Racist, But No 1 with Racists".

The dig at Fox, perhaps aimed at the channel's open support of the conservative Tea Party movement and its frequent criticisms of President Barack Obama, certainly worked up the temper of the notoriously prickly Fox News anchor Bill O'Reilly. In his show O'Reilly showed the clip and then said of The Simpsons: "Pinheads? I believe so."

Liberal fans of The Simpsons, who have long wondered how the show gets away with its radical jokes while being part of Fox, owned by News Corp, looked forward to the show's next episode for a continuation of the fight. It duly happened when the slogan on the Fox helicopter was changed to "Unsuitable for Viewers Under 75".

But when that episode was posted on the internet via Fox and Hulu, the dig at Fox was gone. Instead there was a joke about Homer Simpson and King Kong. Many pundits wondered: had the show gone too far in mocking its owners and had Fox finally struck back? Sadly for conspiracy theorists everywhere, the answer appears to be no.

In response to a flood of concern about censorship, the executive producer of The Simpsons, Al Jean, has broken cover to explain the disappearance of the joke. Jean said the team had been so eager to get in their second anti-Fox gag that they rushed it into last Sunday's episode just in time to appear on TV in North America but too late for other master copies.

"To save money we just put it in the one master that's for the US and Canada but not into versions shown in foreign markets or on the internet," Jean told the New York Times. Indeed, Jean confessed that feuding with Fox suited not only The Simpsons but also Fox as it created headlines and interest in the show. "Both ends of it benefit the ultimate News Corp agenda. We're happy to have a little feud with Bill O'Reilly. That's a very entertaining thing for us," he said.

The fact that the programme did not, in fact, back down from feuding with Fox should not really be a surprise. It has a long history of mocking Fox and its conservative leanings as well as taking on other controversial subjects.

Earlier this year the show allowed British street artist Banksy to guest-create its opening sequence. Banksy took on the issue of sweatshops and factory labour and ended up showing the 20th Century Fox logo surrounded by barbed wire.