It appears that developing The Witcher 3 at CD Projekt Red was all about fun.
There was one point when we were like let’s implement this whole skidding thing that Geralt does when he’s on the slope. And people had just too much fun [so] they decided to try this on this mountain and fix Geralt’s texture so he looks like a snowboarder and they just let him go and made him skid [down].
Len de Gracia
What more, there was a bug with all undone (ctrl-z) content being dumped at a secret 0.0 coordinate in the game. Then the team finally found the mistake.