Mitchell limped from the field in just the 14th minute and did not return - but he had already made an impact on the match after scoring an early try.
After a disciplined first half performance the Dragons fell away in the second term, completing just nine of the 17 sets of possession as they crashed to a fourth consecutive loss.
The performance of rookie winger Mathew Feagai was one positive for the Dragons and he ran 198 metres with the ball, but errors proved costly for the Red V.
