"He said it was the hardest thing in the world."
Hader was stunned.
Hanks played one of the toughest live action roles in recent decades - a plane crash survivor alone on a tropical island in Cast Away.
"I was like, 'You were in Cast Away, dude'," Hader told Hanks.
"And he was like, 'It was harder than Cast Away'."
Cloudy with a Chance of Meatballs, loosely based on Judi and Ron Barrett's children's book of the same name, went on to earn US$249 million ($306 million) at the global box office.
Hader, who played inventor Flint Lockwood, did endure long, physically exhausting days in the voice booth, but that hasn't deterred him from returning for the sequel, Cloudy with a Chance of Meatballs 2.
His voice cast co-stars Anna Faris, James Caan, Neil Patrick Harris and Benjamin Bratt also return.
The family-friendly movie begins where the first ended, but new food-related mayhem reigns when Lockwood's food-making machine spits out living animal-food combinations.
Hader said voicing a character in a sound booth while imaginary food animals were chasing him was just as tough as dodging meatballs falling from the sky in the original.
Movie preview
Who: Bill Hader
What: Cloudy with a Chance of Meatballs 2
When: Opens at cinemas on Thursday
- AAP