In that case:
- After the group entered in the garage, Kalladin stretched his hand outside the window and placed Vin’s head on the roof, the head was dragged by the rain and fell on the floor.
- Even if Kalladin didn’t throw the head, he rolled it or used a similar method so that the head would end up outside the garage.
- Kalladin put the head near the entrance to the garage, so it only looked like it was outside the garage.
- Vin’s head was seen inside the garage, the text is misleading people into thinking the head was outside, but since Kalladin was inside the garage he simply displayed it when the group left the garage.