NEW YORK (AP) – Jon Stewart was right. As promised, his rally was fun.

Then, at the end, he took a few moments for "some sincerity". For some viewers, those clearly heartfelt remarks on the innate goodness of Americans may have upstaged everything that went before.

Fun was about as specific as Stewart had gotten in the weeks leading up to the Rally to Restore Sanity and/or Fear, which he hosted and produced with fellow Comedy Central star Stephen Colbert.

Exactly what the rally would be, and what big names might show up for it, had been a guessing game for fans of 'The Daily Show' and 'The Colbert Report', as well as the media, for weeks beforehand – at least until Wednesday, when a few names leaked. On Saturday, viewers of Comedy Central's live telecast – and online streaming – of the three-hour shindig saw a dandy music-and-comedy concert with an inarguable social message. It was staged on Washington's National Mall, with the US Capitol as the glorious backdrop.

The overarching theme was to redeclare Americans' ability to get along and work together, regardless of their ideological differences. And to chastise the media and politicians for promoting polarisation. To put this message across comedically, the rally harnessed the familiar on-air personalities of Stewart, who, as anchor of the 'Daily Show' satirical newscast, radiates bemused reasonableness, and Colbert, who inhabits a bloviating right-wing pundit on 'The Colbert Report'. Their make-believe clashing in comic bits during the rally was exemplified when Colbert defended the value of unreasonable fear, as in the Garden of Eden.

"If Eve had just had a healthy phobia of snakes, she would not have eaten that apple and cursed us all with original sin," he blustered.

"Then I'd be able to walk around naked everywhere."

"You're just creating bogeymen," Stewart protested.

"Bogeymen?" Colbert erupted in alarm. "Where?"

Later, Stewart introduced Yusef (once known as pop star Cat Stevens), who sang his gentle 1970s anti-war anthem, 'Peace Train', until Colbert brought out Ozzy Osbourne, who ripped into his classic hit with lyrics including, "I'm going off the rails on a crazy train".

These dueling songs led to a standoff, which was settled when the O'Jays arrived to perform 'Love Train'.

Other musical guests included the Roots, John Legend, Kid Rock, Sheryl Crow, Jeff Tweedy, Mavis Staples and Tony Bennett, who sang 'America the Beautiful'.

But the proceedings never strayed too far from funny business, however pointed.

Addressing a crowd in the tens of thousands, Stewart reminded them: "It doesn't matter what we say or do here today. It matters what is reported about what we said or did here today."

Demonstrating how the media could slant a given event in wildly different ways, he let two of his 'Daily Show' correspondents take a whack.

Wyatt Cenac described the throng as "freedom-loving patriotic Americans brought together by the common optimism of a perfect future," while Jason Jones in his mock report said they "seem like a disorganized mass of activists here to push their own pet cause or grievance."

An overlong climactic set piece found Stewart insisting that Americans can come together and solve problems, with Colbert arguing, "The American people can't work together on anything! They cannot stand each other!"