When Rocky is playing Pole Position at the pizza place, the kid to ther right of him is playing Super Mario Bros. 3 on a Play Choice 10. Super Mario 3 was the game that Tum Tum was playing in 3 Ninjas (1992).
In addition to being the only film not to feature the boys' parents, it is also the only one where the boys' real names (Samuel, Jeffrey and Michael) are never mentioned. They are only called by their ninja names in this film.
The last film to be directed by South Korean filmmaker Sang-ok Shin (credited under the name Simon Sheen). In 1978, Shin and his wife Choi Eun-hee were kidnapped by the North Korean government and forced to make propaganda movies for 8 years. The couple managed to escape during a Vienna Film Festival in 1986 and were granted political asylum by the American embassy.