Please read Alexey Sklyarenko's annotations on Pale Fire, Ada and other Nabokov works here.
When Van and Ada look at the photographs in Kim Beauharnais’ album, Ada mentions their red boat Souvenance visible through the rushes:
In an equally casual tone of voice Van said: ‘Darling, you smoke too much, my belly is covered with your ashes. I suppose Bouteillan knows Professor Beauharnais’s exact address in the Athens of Graphic Arts.’
Describing his performance in variety shows as Mascodagama, Van Veen (the narrator and main character in VN’s novel Ada, 1969) mentions a clash of cymbals in the orchestra:
In his Commentary to Shade’s poem Kinbote (in VN’s novel Pale Fire, 1962, Shade’s mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions an especially brilliant impersonator of the King, the tennis ace Julius Steinmann:
Describing the family dinner in “Ardis the Second,” Van Veen (the narrator and main character in VN’s novel Ada, 1969) mentions the great bronze bowl with carved-looking Calville apples and elongated Persty grapes:
According to Kinbote (in VN’s novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla), Jakob Gradus (Shade’s murderer) is the son of a Protestant minister in Riga:
Describing the occasion on which he saw the Shades for the first time, Kinbote (in VN’s novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions his powerful red car and the gestures of a sower, with which Shade distributed handfuls of brown sand over the blue glaze:
Describing the Zemblan Revolution, Kinbote (in VN’s novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions the Modems (Moderate Democrats):
Describing Gradus’ trip from Wordsmith Library to Judge Goldsworth’s house in New Wye, Kinbote (in VN’s novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions the trilby that he hopes was forgotten by Gradus in Gerald Emerald’s car:
Gradus returned to the Main Desk.
"Too bad," said the girl, "I just saw him leave."
Describing his life in Paris in the 1930s, Vadim Vadimovich (the narrator and main character in VN’s novel Look at the Harlequins!, 1974) quotes a poem in which zvezdoobraznost' nebesnyh zvyozd (the stellate shape of heavenly stars) is mentioned:
In his Commentary to Shade's poem Kinbote (in VN’s novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions Hodinski, Queen Yaruga’s lover and goliart (court jester) who is said to have forged in his spare time a famous old Russian chanson de geste: