copied figure produces unwanted scatter points

I am using quiverc from the exchange site to produce some current vectors and it produces the figure as expected (i.e. arrows) over a shiptrack plot line previously created by plot. There is nothign wrong with the plot. If i save this figure (both through command line and as -edit-copy figure- form the window) it adds 'scatter points' to the ends of the arrows (as if i've plotted the ends of the arrows as a scatter diagram), which looks rubbish, especially as the scatter points aren't always the same colour as the arrows! It doesn't do this when saved as a bitmap but the quality isn't good enough to use.

help! any ideas?