Apparently he did not apologise at Cannes for The Brown Bunny:

Actor-director Vincent Gallo has denied apologising for his derided road movie The Brown Bunny - and dismissed US film critic Roger Ebert as a "fat pig" for saying that he did. [...]
In the wake of his film's reception, Gallo was reported to have officially apologised to journalists for having the gall to inflict it upon them. This apology was reported by Ebert in the Chicago Sun-Times and by other papers around the world, including the Guardian.
Now Gallo insists that he did no such thing. "I never apologised for anything in my life," he says. "I like the movie. I had 100% creative and financial control over it, and if I didn't like it, I would have changed it.
"The only thing I am sorry about is putting a curse on Roger Ebert's colon. If a fat pig like Roger Ebert doesn't like my movie then I'm sorry for him."

Ah, there really is something almost heroic about Vincent's unpleasantness, isn't there? I'd feel sorry for him if I thought it could be pinned on the mental problems he appears to suffer from, but I suspect he is, in fact, just a natural twat.

Meanwhile, Roger Ebert responds at length:

During a scene where Gallo shares a bicycle with a young woman, I became so nostalgic for "Butch Cassidy" that I softly sang "Raindrops Keep Fallin' on My Head." I stopped after six words when my wife jabbed me in the ribs. I was overheard by a writer for Hollywood Reporter, who included it in his coverage about how badly the film was received, and that is another reason Gallo has put the heebie-jeebie on my colon and prostate. I am not too worried. I had a colonoscopy once, and they let me watch it on TV. It was more entertaining than "The Brown Bunny." [...]
On Monday Gallo told the New York Post's Page Six that Screen International "made up" his quotes. He added, "I'm sorry I'm not gay or Jewish, so I don't have a special interest group of journalists who support me." Such comments might seem politically incorrect, but not to Gallo, who says he is a conservative Republican, although since his film ends with a hard-core oral sex scene, he is not likely to be fielding many group bookings from the Moral Majority.
But was Gallo actually misquoted?
"Absolutely insane stuff from Gallo," editor Colin Brown assured me. "Not only is everything we wrote in Cannes exactly as he spewed out, word for word, it was all recorded on audio tape." He added, "It makes me wonder whether this is not all some great marketing ploy on his part. I have actually come across people who say 'Brown Bunny' is top of their list of films they most want to see out of Cannes this year."

Well as I believe I said at the time, I want to see it myself, though I suspect that those other people are like me and only want to see it so they can tell if it's really that bad...