I turn to Ferrell and ask which was the harder to master, his singing for the disco tracks or his basketball moves?
"I'm just finishing my caricature drawing of Woody," replies Ferrell. "I'm sorry, I totally forget your question."
I ask again. "Well it definitely wasn't basketball, I'm a pretty gifted athlete. I always wanted to do a basketball movie so this was a dream come true. But I've never been a '70s pop singer before, so that was new.
"For that I went to a funk camp, directed by Isaac Hayes, which is located up in Vermont. You just sing and he watches you from the other room. It's a very creepy camp actually. Nothing bad happened!"
Andre Benjamin, the musician and actor who is one half of the acclaimed music duo Outkast plays Clarence Withers, the flamboyant superstar of the Tropics.
"I guess he's the most athletic of them all," says Benjamin. "He has this natural ability from the neighborhood or from the playground style of playing. He likes to go for all the shots and doesn't like to pass the ball. He doesn't even run down the court to play defense."
Ferrell was impressed by Benjamin's contributions to the film. "For Andre to be thrust into a comedy like this and have to be the best player on the court, he's been amazing. He brings his whole charisma to the film. And he may be the most stylish person I will ever meet in my life."
The only question that remains, in the light of all their antics, is did they have as much fun filming Semi-Pro as they do discussing it?
"Did you ever hear the expression 'by the numbers?'" Harrelson deadpans.
"Showing up on that set every day and watching them go it was hilarious," says Benjamin. "You learn a whole new level of respect for comic talent. They're really professional. They know how to turn it on."