Comprehensive music list
A few people have taken a stab at it, but here is (I believe) the first complete list of the music from Hopscotch, and when the music is heard. Please note any errors or omissions.
1. Street march at beginning: Erzherzog Albrecht Marsch by Karl Komzak
2. Drinking song in beer hall: Kennst du die Perle by Karl Ganzer
3. Salzburg outdoor cafe: Sonata in A (KV 331) by Mozart
4. In Isobel's home: Sonata in A played by string quartet
5. Gin rummy scene: Romanze from Eine Kleine Nachtmusik by Mozart
6. Morning after: Sonata in A
7. While typing with Isobel: Rondo in D (KV 382) by Mozart
8. Crossing Switzerland border: Largo al factotum from Barber of Seville by Rossini, sung by Tito Gobbi
9. Getting illegal IDs: Rondo in D
10. Driving in GA to real estate agent: Rondo in D
11. Typing at Meyerson's: Rondo in D
12. The next morning: Serenade from Eine Kleine Nachtmusik
13. Delivery of pickup truck: Trio from Symphony #40 (Mozart)
14. Removing luggage at Meyerson's: Rondo in D
15. Gun battle at Meyerson's: Un Bel di Vedremo from Madame Butterfly by Puccini
16. Chase with pickup truck: 1st movement of Posthorn Serenade (KV 320) by Mozart
17. Isobel drives off of hovercraft: Rondo in D
18. Cutter tied up in room: Rondo in D
19. Early morning race to airfield: 1st movement of Posthorn Serenade
20. Race from police station: 1st movement of Posthorn Serenade
21. Dogfight: Non Piu Andrai from The Marriage of Figaro by Mozart, sung by Hermann Prey
22. Bookstore: Rondo in D