Speaks fluent English, Cantonese and Mandarin.
Studied Tae Kwon Do under Philip Tan in 1983 on the set of Indiana Jones and the Temple of Doom (1984), and has also trained in the art under Tao-Liang Tan.
When phoning his mother during the Indiana Jones and the Temple of Doom (1984) movie shoot, he referred to George Lucas and Steven Spielberg as bearded man 1 and bearded man 2.
His brother was the one actually auditioning for the role of Short Round in Indiana Jones and the Temple of Doom (1984). Jonathan just followed his brother along, but the casting people decided to pick him instead.
Attended Alhambra High School in Alhambra, California, USA.
In the scene in The Goonies (1985), where rocks are falling from the cave ceiling, he screams "Holy S-H-I-T", spelling the expletive rather than saying it. He did this because his mother made him promise not to use any bad language in the movie.
Was number 67 on vh1's The Greatest: 100 Greatest Kid Stars (2005)
Is a huge Jackie Chan fan.
He is now a martial artist and working as a stunt coordinator, recently worked with Jet Li on "The One" 
Graduated from the University of Southern California School of Cinema Television.