It took me a while to figure this out, but now I can't unsee it, and it's bugging the bejesus out of me.
In this picture, Kennex clearly has a below-the-knee amputation.
But in this one from the pilot:
It's obviously high above the knee. Additionally, the leg Dorian gives him in the season finale is for an above-knee prosthesis.
Dammit, props department, how hard is it to keep the core fact of your protagonist's convenient disability straight?
And on a shallow note, John's legs are lovely.