After the fight in the Park, Lukas runs into the U-Bahn. In the first shots, a car of type H is arriving at the station and Lukas enters it and looks up to the ceiling, in the following shots he is in a older car of type F.
When the pawn shop owner checks the PC, you can see that the desktop is actually empty. There is no power supply and no external connectors (for mouse/keyboard, sound, network or graphics) visible.
When the guys try to pawn off the PC, blue USB ports are visible on the front of the device. Blue USB ports are typical for USB 3.0 which was not finalized until 2008.
At the time the story takes place, the metro line U7 didn't have any passenger infotainment screens in the train. There were only some mounted in the trains of the U9 line.