Page 32. " 'I want to tell you,' the voice on the phone said. 'My head is filled with things to say.' "

The first lines to the Beatles song "I Want To Tell You", written by George Harrison. 

'I don't mind,' Hal says. 'I could wait forever'. These are further lyrics to the song, though not the next ones.

Listen on Spotify: Tribute Version

Page 33. " as would anyone who refuses to eat pretty much anything but Toblerone "

Toblerone is a Swiss chocolate bar, known for its triangular shape, based on the Swiss Alps. 

Toblerone
Creative Commons Attribution Share AlikeToblerone - Credit: Znode

Wallace referred to the confectionery in his 1990 essay 'E Unibus Pluram: Television and U.S. Fiction', pointing out that treats are acceptable but only in moderation: "One can only guess at what volume of gin or poundage of Toblerone six hours of Special Treat a day would convert to".  The essay can be found in A Supposedly Fun Thing I'll Never Do Again.

Page 41. " You listened to Tosca over and over "

Tosca is an opera by Italian composer Giacomo Puccini (1858-1924).

This is referred to again much later in the book (page 896 - "There is no music for free-floating misery like Tosca") just before Hal's facade of emotional antipathy (prompted by his father's death and sustained through years of drug-use) finally slips, and he feels "some variant of the telescopically self-conscious panic that can be so devastating during a match."

Listen on Spotify:

Vissi d'arte from Tosca

An Introduction To...Puccini Tosca: Historical Background To Tosca