The map doesn't seem wrong to me? It seems to me the arrows are just pointing at specific locations (from which the reformation spread), rather than suggesting movement from one end of the arrow to the other (direction of the reformation's spread).
Yes, but even with that assumption some of the arrows are decidedly off target. The arrow for Henry VIII does visibly not point at neither London nor Canterbury, and most of the important stations of Luther's life were in what would be East Germany on that map yet the arrow goes clearly past it, and even if the creators of that map deemed the Diet of Worms to be the most important event... well that arrow also misses that.
Also the map is not really that much informative. They could have completely omitted those arrows and simply print the names directly into the countries.
pic unrelated