I think anyone who has ever done an oil change on a 102 or 103 motor knows whats happening here.
The oil filter on these 2 engines are spin-on and "inverted" from what you would think of as "normal". You have to very carefully loosen the filter to allow the oil to run into the engine and drain out. If it is loosened too much, it will empty mostly down the drivers side of the engine, just as you observed, towards the rear of the motor. I know I'm as guilty as the next guy of loosening a little too much at times, with the results you have observed-an oily mess for a day or so after the change.
ps If memory serves, the oil level sensor is on the drivers side of the engine also, about in the middle. It mounts to the side of the oil pan. Maybe slightly forward of the middle.