The Detroit Subway (aka. Detroit Metro Rail) is a fictional rapid transit system with an unknown route length and unknown amount of stations that was featured in the background of the scene in RoboCop 3 where Nikko Halloran and three Rebellion members break into the Security Concepts headquarters and encounter and battle an ED-209.
In reality, the filming location was in Atlanta, Georgia and the train scene in the background is a MARTA rail train.[1]