I spawned my character at a station, can't remember what it was called, hopped into a passenger train and was running up the aisle, when I randomly fell out of the train. The screen went black and I spawned in a different area, no idea where. I could walk around, but then fell through the ground and could clip through walls until i fell into an infinite whiteness.
I experienced this once as well. And just like you I don't exactly recall on what service line it was. I do vaguely remember though for me it happened in Rapid Transit.
