The scene after Chuck falls asleep features a “ Christmas dinner” with Kelly’s relatives, played by some terrific actors, including Joe Conley, Dennis Letts, Nan Martin and Timothy Stack. In a prior scene, after Chuck returns from Moscow, he falls asleep on the couch of his home with Kelly, while a CNN anchor announces that “Just days before Santa departs on his annual gift-giving venture, he’s been declared physically fit to fly,” and then declares that “Santa Clause took off into the wild blue yonder for an early start,” presumably meaning prior to the traditional Christmas Eve start of Santa’s journey.
By my interpretation, within the film, it’s clear that the flight is on Christmas Eve. Some sources online indicate that Chuck’s flight is on Christmas Eve, while others state that it’s Christmas Day.