The Free On-line Dictionary of Computing (30 December 2018):

mouse trails

    A feature (usually of Graphical User
   Interfaces) which causes the mouse pointer to leave a
   trail across the screen.  This is done by keeping track of the
   last eight or so (maybe configurable) pointer positions, and
   only erasing the oldest.  This means that at any time, there
   may be up to eight pointers on the screen, but if the mouse is
   still, they will all be in the same position, and so only one
   will be visible.  When the mouse moves, it appears to leave a
   trail of pointers behind it, and this can dramatically
   increase the visibility of the pointer when using LCD
   screens.  The older ones had such long persistence that a
   single mouse pointer, when moving, tended to be completely
   invisible, and on a cluttered screen, was very difficult to
   find.

   (1996-07-08)