Stephen's attachment to the ball
I did love his anecdote about how the ball came about. Though the way he describes being electrified by Chloe watching him carries more weight re: the nuts and bolts of their attraction than it should, since we're missing so much detail. ;)
Also, we never really get to see Stephen play tennis! Would have loved some kind of video playback of a match (after Gustave describes his penchant for arguing with refs, I kind of needed to see THAT)... still, just a photo would have been great.