Korean pop star Rain had no martial-arts experience prior to filming. He trained extensively for six months in martial arts and weapons handling with stunt and action choreographers Chad Stahelski, Peng Zhang, Jon Valera and Jonathan Eusebio as well as weights and cardiovascular workouts with personal trainers; he also went on a diet of chicken breasts and vegetables.
Since Mika gave Raizo the homing capsule, his former ninja colleagues shouldn't have been able to leave the country with him. However, the authorities would have had to let the clan take Raizo back to their home dojo in order to locate it.
There is one shot of Raizo walking through Berlin that was probably not shot on location, as the German in the advertisement in the shop window behind him is nonsensical.
Mika Coretti: I know you can't hear me, so I'm sure this doesn't matter but I'm going to say it anyway. I'm just a forensic researcher. It's like a fancy way of saying I'm a librarian. By myself I can't do anything to help you, but I wanted to thank you for saving my life. And I hope you can forgive me for this.
What content advisories are concluded in this film?
A
The following advisories are provided by Home Box Office Rated R for: Graphic Violence, Adult Content, Adult Language.(HBO advisory)
Q
What are the differences between the censored Singapore Version and the Uncensored Version?
A
In Singapore only a cut version of this movie was released in order to get a rating. This censored version misses out nearly 45 seconds of violent scenes that are featured in the uncensored versions. A detailed comparison between both versions with pictures can be found here.