First, let's dispel some of the misinformation about this film. It's not "like 300" (there is a scene in the film lasting a few minutes which emulates the aesthetics of "300", which itself mimics the "bullet time" technique in "The Matrix"). There is no relation to "South Park" (???). And the only real similarity the movie shares with "City of God" is that it takes place in an impoverished area in Brazil (and it is increasingly agitating to read reviews about Brazilian films or films that take place in Brazil which constantly reference "City of God").
The story in "Plastic City" revolves around a counterfeit goods smuggler named Yuda (played by Anthony Wong) and his adopted son Kirin (played by Jo Odajiri), who are facing the end of their business as a result of the economic and political changes of globalization. To facilitate Brazil's integration into the global economic system, Brazilian politicians have initiated an anti-piracy and anti-counterfeiting campaign to clean up the country's international image that threatens the livelihood of some of Sao Paolo's most impoverished communities who depend on this illicit economy for a living. Meanwhile, with permanent relocation of production facilities to third world countries where the cost of labour and production are cheaper, the demand for affordable brand-name and designer products traditionally supplemented by illicit counterfeit merchandise is slowly being filled by surplus or "left-over" goods coming from the factories contracted by brand-name companies that have fulfilled their quota. A Taiwanese businessman approaches the father and son with an offer that would help their "business" transition from counterfeit import to surplus import (equally illicit). Yuda resolutely rejects the offer, thus starting a "war" that mobilizes politicians, street gangs, and mercenaries.
This premise could have been developed in any number of interesting directions. The problem is that Nelson Yu seems to have gotten bored with just making a political commentary, and decided to focus on telling a story about the relationship between Yuda and his adopted son (that unfortunately turns out to be not very interesting at all). The story ends up being poorly paced as a result of the fixation on interpersonal relationships (that do not always advance anything related to the plot), with the last 1/3 the film stitched together by a series of disconnected scenes meant to convey certain symbolism and metaphors about "tradition vs. modernity" that, quite frankly, I couldn't be bothered to make sense of because neither the story nor the characters made it worth the effort. Anthony Wong does what he can, given the script and the direction he has to work with. Other than admiring his performance, there isn't much else I found entertaining about this film.