Yester-day, I learned the solo in "What You're Doing" (I'd forgotten that I learned it before, but I never wrote it down; compared to my old recording, what I have now is more accurate, anyway). In the first half, I think there's a glissando'd double stop: A+C# slid down to G+B. Provided I have the parts figured out correctly, this same figure (played an octave higher) is also in the choruses in "Every Little Thing."
The songs are in different keys ("What You're Doing" is in D major, and "Every Little Thing" is in A major), but using this same figure in both gives some cohesion to Beatles for Sale.