Greg, I appreciate that it's a fine line that all Trek authors walk, and I have to admit that sometimes the excessive continuity references really annoy me. On the other hand, just the right amount actually makes me feel good.
Where is that line? It's hard to say.
What would be more realistic would be to also have memories that don't refer to old episodes, but then you'd get readers who do nothing but say "what episode did that take place in?"
So you can't really win. You can just do what makes you feel comfortable.