The lavatories on the train are labeled "Bad", which translates to "bathroom". Lavatories on German trains are labeled "WC" - a "Bad" in Germany usually features a tub or at least a shower.
Almost everything about the train does not exist in Germany: The door knobs are American, you cannot go outside a wagon in German trains, signal flares do not exist, all rail tracks (especially around Frankfurt) have power lines above them, there are no luggage wagons with sliding doors etc.
You cannot sabotage pneumatic air brakes on trains as they are fail-safe. Pumping air into the brake pipe system releases the brakes. If you release all the air in the system, the brakes will apply.
If the engine were running backwards, once it stopped going forward, it would not stand still, but immediately begin running backwards.
Although the exterior of the building shown as Frankfurt Main Station resembles the actual station quite closely, it is different building. Frankfurt Main Station is at the same level as the street and has no stairs in front of it. Also, the surroundings shown on the show don't match the actual neighborhood.