X, the poop stuff, any details, are believed by script writers, writers in general, writers of any ilk, to make a story line more credible. Stuff like that would be anticipated. A writer would expect the poop were he or she reading this as script. If you are reading it as a scientist, you think, "why the poop?".
They tried to make the thing more "realistic". Pretty dumb, given the fallout.
And yet, when they describe the TLI burn (two for the non-free-return trajectories) they apparently talked to enough scientists to get the details right. When they describe lunar geology, same. Telecommunications, same.
For that matter, there are multiple papers on the physiological findings of humans in space; tables of changes in bone density, white blood cell counts, plotted heart rates over the missions. And of course accurate tracking of consumables including oxygen, water, CO2 scrubbing, even (if you look) totals for waste.
So they DID have doctors they could consult with while writing the script. Were they sick the day Apollo 8 was scripted? And why just them, when a dozen other professionals were in the room concocting a narrative that stands up to scrutiny from professionals in the field TODAY?