Factual error: In the bowling alley scene, Jack's friend tells him that Kate is well-liked in all of Union County, but in the movie, Jack and Kate live in Teaneck, which is in Bergen County.
Factual error: The movie, set in December 2000, depicted Christmas Eve as a weekday although it was actually Sunday.
Answer: More of an alternate reality. He really was living the life he'd have lived if he'd come back from his flight. The "angel" placed Jack in an alternate reality, then put him into the past in his original reality after he'd learned from his experience.
Phixius ★