Sometimes no matter you do, you get glitches. You can try clearing the image cache and see if that helps, but you could spend more time chasing the glitch and re-rendering than it’s worth.
Try rendering out the image sequence and if it comes to it, saving the individual frame from the comp and use that single frame to replace the glitch. This might actually reveal the problem or let you just skip past it.
I think rendering an image sequence is your best bet too. Or just try rendering a still frame of that one bad frame and see if you get the issue still. Maybe you can just duplicate the frame before it to cover the glitch if it's just that one frame.