Things I noticed for the first time
Watching the film yesterday, I just noticed things that relate to other Grant/Hepburn movies:
Grant - Taking a shower in a woman's hotel room and hanging by just his hands were also featured in North by Northwest.
Hepburn - I also like the "on the street where you live" reference to the song by that title from My Fair Lady.
Don't know how these things could have gone over my head on previous viewings.
Anything else that I missed?