An L-train was planned to be used as an interactive element in at least one multiplayer map. Scripting and a kill icon can still be found in the games code, however, none of the released maps feature a subway system, so it's unknown where this might have been used.

The script reveals that it would have been a 24-car train, causing rumble effects, moving at 1200 units/second every 100-200 seconds, shaking the screen of anybody standing nearby and killing anyone standing in its path.