Infernal Affairs - watch online: streaming, buy or rent
Currently you are able to watch "Infernal Affairs" streaming on Rakuten TV for free with ads or buy it as download on Rakuten TV, SF Anytime, Viaplay. It is also possible to rent "Infernal Affairs" on Rakuten TV, Viaplay, SF Anytime online
You can also stream the title for free on Filmstriben.