Oscar-winning director Ang Lee played an important role in The Hangover Part II - he's the father of one of the actors.
Mason Lee plays Teddy, the teenager the lead characters try to rescue as they struggle to piece together what happened during a crazy night in Bangkok.
Ang Lee was clearly a proud dad speaking to reporters after catching a showing with his younger brother and mother earlier this week in Taiwan, his home country.
"My son's performance was quite good," Lee told reporters outside a Taipei theatre in footage posted on the website of the Taiwanese newspaper Apple Daily. "He is quite a serious actor but this is just a comedy."
Asked by an overeager reporter whether Mason was a future Oscar winner, the elder Lee responded with a smile, "He only has a small role in the movie."
Lee demurred when asked if he would cast Mason in one of his movies.
"I don't know. Kids should do whatever they want to do," he said.
Lee's older son, Haan, played the toddler son of the family featured in Lee's 1992 directorial debut, Pushing Hands.
The Associated Press didn't touch on Mason Lee's performance in its largely critical review of The Hangover Part II.
It gave the sequel one-and-a-half stars out of four, saying it was too much of a rehash of the first instalment.
However, the movie has been a big international hit. It was the No. 2 film outside North America behind Pirates of the Caribbean: On Stranger Tides last weekend, raking in US$63.8 million (NZ$77 million) on its second weekend.
Its total take as of last weekend was just over US$347 million (NZ$419 million).
Lee, who won a best director Oscar for the gay romance Brokeback Mountain, was in the Taiwanese capital shooting his adaptation of the award-winning Yann Martel novel Life of Pi.