Early drafts of Gabe and Lian were of having Gabe with buzz-cut army style haircut, and Lian with short red hair. These drafts however evolved into Gabe and Lian as we know them now and can be seen as a secret code on _Syphon Filter 2_ (2000).
Due to SCEE wanting a more commercial friendly "not under 16" rating from the USK in Germany, the game's German version was modified to remove the blood from cutscenes and have all in-game red blood recolored green.