This is not an exhaustive list, as I have omitted most of the scene change music, but gives some idea of the range of extracts used. Note that the words quoted are the titles in the original G&S versions, and may not be the words used in the actual adaptation - in fact, one of the trickiest things is to learn to sing the 'wrong' words to the music - and then, having learned them, to go back to the originals!!
Act I:
Carol Singers: ‘It came upon a midnight clear’.
Scrooge: Oh, why am I moody and sad? – Ruddigore
Fred: Good Morrow, Good Mother – Iolanthe
Orchestra: The incantation music from Iolanthe
Chorus: Painted Emblems - Ruddigore
Marley: 'beware beware beware' - Ruddigore
Chorus & Mrs Cratchit: Melange:You understand? I think I do – Ruddigore, Of happiness the very pith – Gondoliers, Now hearken to my strict command - Princess Ida, Let’s give three cheers for the sailor’s bride – Pinafore, Pour, oh, pour the pirate sherry – Pirates
Mrs Cratchit, Bob & children: Brightly dawns our wedding day – Mikado
Scrooge: Major General recitative, Act II - Pirates of Penzance
Xmas Past & chorus: Fairy Queen Incantation: Iolanthe
Orchestra: arrangement of When the Night Wind Howls - Ruddigore
Chorus: Now to the Banquet we press – Sorcerer
Young Scrooge & Isabel: When alone together – Gondoliers
Young Scrooge, Isabel & chorus: This very night – Pinafore
Fezziwig, Elizabeth, Young Scrooge, Isabel & chorus: A Nice Dilemma - Trial by Jury
Chorus: Oh joy, oh rapture unforeseen - Pinafore, and With joy unbounded – Trial
Isabel: Alone, and yet alive – Mikado
Chorus & principals: Oh Marvellous Illusion, O Terrible Surprise! – Sorcerer
Act II:
Orchestra: Christmas Present march
Scrooge: The hours creep on apace – Pinafore
Orchestra: The ghost of Christmas Present music starts - Sentry’s song from Iolanthe, with other counter melodies
Chorus: For the merriest fellows are we - Gondoliers
Scrooge: Mad Margaret’s song – Ruddigore
Gravediggers & chorus: The Graveyard Gavotte
Gravediggers & chorus: Away, away - my heart’s on fire – Pirates
Chorus: Funeral march from Yeoman
Chorus: Onward Christian soldiers
Mrs Cratchit: The hour of gladness – Mikado
Isabel & Scrooge: There was a time, a time forever gone – Gondoliers
Chorus: Oh fool, that fleest my hallowed joys - Finale Act I: Mikado
Chorus: With joyous shout and ringing cheer - Finale: Mikado