In the movie, which is based on a true story, Corbett plays a teacher whose goal is to help a group of special-needs children achieve their dream of going to space camp at NASA.
Working with kids was something brand new for this veteran actor.
"This was an experience that I'll never forget. I made a lot of lifelong little buddies there, and these were some special-needs kids. We have autistic kids and Down syndrome, anger management kids and Tourette's, but it was just kind of eye opening," said Corbett.
Though many Hallmark movies are tear-jerkers, Corbett said the movie's producers made a conscious effort not to make it a sob story.
"People have that pre-conception of a Hallmark movie. So James Sadwith, our director, he kept saying, 'I don't want to go for the tear thing in this one. I don't want to go for the violin moment,'" Corbett said, though he admits that the movie does have its moments.
"Ultimately, it's like the Titanic. You know what's going to happen. You know these kids are going to go to space camp and get something out of it," he said. "I think it's an appropriate tissue-grabber, too. I don't think we try to hammer it over the head."
"A smile as Big as the Moon" airs Sunday at 9 p.m. on ABC7.