This may have crossed your mind, what happens if I lose my internet or Zwift crashes mid-ride? All is not lost, as I found out from Andy at Hells (Everesting).
When I asked Andy that question he said: In the event of a system crash, just ask your rider to start a new activity, and they can either stitch the two files together afterwards, or submit one file and link to the other, either option is fine.
I was planning on taking the following screen shots during the day on my Zwift companion app:
Taking a photo at the base of the hill prior to each climb and after you have passed under the banner at the top. Having these could be helpful if you have a major crash.
If I experienced a loss of internet or a system crash, after getting everything back up and running, I would simply request to ride with someone (that I follow on Zwift) that was a little lower on the climb than I was when it crashed. Once in, I would take a photo of where I was, upon restarting. After the ride as recommended by Andy, from Hells I would have two files to submit, I would likely be over cautious and ride a bit extra to absolutely ensure I exceeded my goal elevation.
We have lots of time out there, snap those photos at the top and bottom, these with the Zwift/Strava files will be more than enough to satisfy the folks that will enter you into the Hall of Fame.
No need to be nervous - enjoy the ride!

- Darcy Haggith, President, Infinit Nutrition Canada