Drew Barrymore still suffers back pain after falling over during a scene in 'Fever Pitch'

Drew told Entertainment Weekly: "There's a scene where I go on the Green Monster, the wall, and I fall and when I did that, I fell really badly on my back.

"And so you'll see me fall and I start wincing and screaming - that was all real. And then I had to keep running anyway, and I still have a bad back. I'm like, 'Did it happen on Fever Pitch?'"

However, the '50 First Dates' star did admit that she had "the best time" working on the Farrelly brothers film alongside Fallon.

Barrymore said: "I loved watching the Farrelly brothers - who were my favourite directors, like Kingpin and Dumb and Dumber, they're still my favourite movies - be sensitive and make a movie that was very funny, but I thought very gentle and emotional.

"I was so happy to see that side of them because they are those guys and I was like, 'Wow, the Farrelly brothers with heart, man. This is awesome.'"

Drew explained that her favourite part of working on the film was seeing the real-life romance that blossomed between Fallon and her Flower Films producing partner Nancy Juvonen - who went on to get married in 2007.

She said of her pal: "The person who changed my life in the most dramatic way, I got to somehow be in something that helped her find happiness.

"She's just my favourite person that I just keep thinking, 'Thank God they found each other. I'm so glad I had anything to do with that.'"

Drew added: "It's the best when you want people you love to be happy, and you get to witness it starting. And so 'Fever Pitch', to me, is the promise that good things happen to good people."