(at around 9 mins) Andre Toulon's hotel room is a detailed reconstructed set to resemble the original room used for the original Puppet Master (1989) film.
Ozu was originally written to be an old man resembling Fu Manchu, but David DeCoteau insisted that the character be a dragon lady instead.
This is the first entry in the series that David DeCoteau directed under his real name since Puppet Master III - Die Rache des André Toulon (1991).
The first installment in the series to be filmed in Asia.
There was a debate with the film staff on whether L.A.'s Chinatown had neon signs during the 1940s or not. David DeCoteau however decided to allow the Chinatown in the film to have neon signs, because to him it makes the town look more lively during the night scenes.