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.
Out of the entire 3 Ninjas quadrilogy, this is the only film which doesn't feature the boys' parents Jessica and Sam Douglas.
This is the only film in the "3 Ninjas" franchise to be rated PG-13.
Michael Treanor's older sister appears in the pizza parlor scene as the girl who says, "Pick up #14" and his older brother also appears in the pizza parlor scene as the boy in the blue striped shirt who asks Rocky, "Can he teach us too?" Chad Power's younger sister also appears in the pizza parlor scene as the girl who asks Tum-Tum what the boys' names are.