Yes, calling c_move 3 times per frame for the same entity.
Usually I code all movement codes so entities float above the ground via c_trace. For this egg I chose to have constant c_move collision because of the non-spherical shape, which probably wasn't the best idea - it works though, except that glitch. (Implying that I cannot set it to passable without redoing the code.)

The visual glitch seems to appear when the result of c_move is <= 0.

EDIT: Btw. putting a passable copy at the same position and angles does the trick as a workaround.