I've heard of 35MM screenings where the compositing didn't look like ass so it could even be as simple as a better transfer of a better print.
You could also clean up the image with a lot of tedious rotoscoping and selective colour grading.
If you had the background plates you could just CG a new runner onto those and save all the hassle -- but then you've got to build, rig, light, animate, and composite a new CG character, and that's not cheap if you want it to not look ass.