At the end of the movie, where Leech is held at knife point, he holds his cigar in his left hand as the assailant forces him to his knees. When the camera angle changes from side to front, the cigar is in his mouth.
The opening text says that pollution killed off all the plants, but in the surface scenes, there is a lot of plant life.
Shortly after Plughead is shot, he speaks to Danner, but his lips do not move.
Danner is a synthetic but requires air and even gets poisoned by the sewer leeches.