Also running Ubuntu (14.04 x64) I don't have any problems. Comparing my settings to yours I only found 3 differences (mine are default I believe and work fine):
What I noticed from testing is that I shouldn't mess with any settings for Mario Kart: default settings work the best. Maybe try turning the configuration options I listed off and see what happens.
- I have widescreen hack turned OFF
I have Skip EFB Access from CPU OFF
I have OpenMP Texture Decoder OFF
What I noticed from testing is that I shouldn't mess with any settings for Mario Kart: default settings work the best. Maybe try turning the configuration options I listed off and see what happens.