Bill Murray claims he only made Garfield because he thought it was a Coen brothers film, and that Kung Fu Hustle is the best comedy ever made. If only all star interviews could read like this

Looking back at Bill Murray's career, there is always an uncomfortable question hanging in the air. Given that he's usually made such impeccable decisions when it comes to taking roles, why exactly a few years back did he agree to make Garfield – the spectacularly bland big-screen adaptation of the well-known comic strip? Just where does this wildly awful comedy about a wisecracking feline fit with the likes of Groundhog Day and Ghostbusters, Rushmore and Lost in Translation?

The answer, or at least Murray's version of it, has finally been revealed in a rare interview. It appears he thought he was making a film with the Coen brothers.

In a hugely entertaining chat with American GQ (during which he also suggests that Ghostbusters 3 is dead in the water and names Stephen Chow's Kung Fu Hustle as "the supreme achievement of the modern age in terms of comedy"), Murray reveals that he picked up Garfield's script and noted that it was written by one Joel Cohen. Mistakenly believing this to be the celebrated co-architect of dark comedies The Big Lebowski and O Brother, Where Art Thou? (rather than the creator of such gems as Evan Almighty and Daddy Day Camp, whose name has an additional "h"), Murray happily signed up. His mistake only became clear when he turned up to record his voiceover. Sample line: "I think I'm going to blow cat-chow chunks!"

"Finally, I went out to LA to record my lines," Murray tells GQ. "And usually when you're looping a movie, if it takes two days, that's a lot. I don't know if I should even tell this story, because it's kind of mean. What the hell? It's interesting.

"So I worked all day and kept going, 'That's the line? Well, I can't say that'. And you sit there and go, 'What can I say that will make this funny? And make it make sense?' And I worked. I was exhausted, soaked with sweat, and the lines got worse and worse. And I said, 'OK, you better show me the whole rest of the movie, so we can see what we're dealing with'.

"So I sat down and watched the whole thing, and I kept saying, 'Who the hell cut this thing? Who did this? What the fuck was Coen thinking?' And then they explained it to me: it wasn't written by that Joel Coen."

Which, you have to admit, is just about the greatest story Murray has ever told – and he has told a lot of great stories. Could it be that he made it all up for comic effect? In the same interview, after all, the actor does admit that even he doesn't really know exactly what's about to come out of his own mouth.

I wonder if, in reality, Murray simply felt (correctly, it turned out) his career would be unlikely to suffer due to a film in which he is effectively invisible to audiences – just as his character in Lost in Translation, Bob Harris, was pretty certain that shooting a whisky ad for Japanese TV was unlikely to ruin his reputation in the US. Or maybe he genuinely believed the Coen brothers had decided to make a Garfield movie instead of, say, No Country for Old Men. We may never know the truth. But if Murray's only reason for signing on for Garfield was a case of mistaken identity, one last question remains: why exactly did he return for Garfield 2: A Tale of Two Kitties?