As for me, this movie is pretty satisfying as a comedy. There are a lot of high-grade jokes among this movie while jokes are very embarrassing in other comedies these days. Except for the humor, the flashbacks amused me very much and I believed this part had been edited surprisingly well. These flashbacks drew a clear and interesting outline of the character's previous life: abused by father, involved in love, betrayed by girlfriend, discouraged by father. Generally, this is a corny movie in which time-travel helps characters clear the misunderstanding of family or friends. However, this movie focus on the sense of humor and thinking of life instead of the science fiction part. In my opinion, the ending is the biggest flaw because there is no intact logical circle. It isn't based on any theory of time travel. The father knew the gesture because the son taught him. However, the son didn't really appear in the father's early life, and therefore, the gesture shouldn't be known. I know that Han Han wanted to write a mysterious ending, but I think it turns out to be the very flaw.