I just finished reading the Splinter of the Mind’s Eye comic adaptation, and while it was okay, I hated how not only does it establish that Luke had actually fought Vader prior to The Empire Strikes Back, but that he was able to best him in combat? What!? How come he is better at fighting before getting Force training? Why do Luke and Vader never refer to this occurance in Empire? Also, why doesn’t Luke use the Kaiburr crystal or ask Halla for help in The Empire Strikes Back? It really messes with the continuity.
Splinter of the minds eye hands down is my most hated piece of EU. As a kid when I read about it in the pre-Disney ultimate visual guide, which detailed the events of the book. And I was soooo confused as a kid. It just messes with so much continuity! That hands down is one of the best pieces of EU that I love was made non-canonical.