The classic diagram of Apollo 13's trajectory is a figure-8 (eg. Wikipedia's illustration). This is clearly drawn in a reference frame that's rotated to align with the Earth-Moon axis. What shape would the trajectory be when drawn in a non-rotating Earth-centered reference frame? My experience with Kerbal Space Program says it would be a near-ellipse, with the "crossover" in the rotating frame being the result of the Moon moving prograde faster than Apollo 13 at that point.
Here is a great GIF showing what it looks like (I modified to speed it up), From this archived page:
You can see that the rotating reference frame view is the same as the inertial. I was trying to find to find enough info to plot it in GMAT to get more data and views, but as of the time of writing I cannot.