Please read Alexey Sklyarenko's annotations on Pale Fire, Ada and other Nabokov works here.
Describing Victor Vitry's film Letters from Terra, Van Veen (the narrator and main character in VN's novel Ada, 1969) mentions Athaulf Hindler (also known as Mittler — from ‘to mittle,’ mutilate) who came to power in Germany in 1933:
In an interview to Alfred Appel (included in Strong Opinions, 1974) VN says that the Zemblan crown jewels (vainly looked for by the two Soviet experts) are hidden in the ruins of some old barracks near Kobaltana:
And as a closing question, sir, may I return to Pale Fire: where, please, are the crown jewels hidden?
The action in VN's novel Ada (1969) takes place on Demonia, Earth's twin planet also known as Antiterra. Describing Victor Vitry's film Letters from Terra, Van Veen (the narrator and main character) mentions an unfortunate extra, who played one of the under-executioners and got accidentally decapitated while pulling the comedian Steller, who played a reluctant king, into a guillotinable position:
The action in VN's novel Ada (1969) takes place on Demonia, Earth's twin planet also known as Antiterra. The narrator and main character, Van Veen is the author of Letters from Terra, a philosophical novel (1891). Van's novel was made into a film by Victor Vitry, a brilliant French director:
In VN's novel Lolita (1955) Lolita tells Humbert Humbert that she was a daisy-fresh girl before their first love-making:
“You chump,” she said, sweetly smiling at me. “You revolting creature. I was a daisy-fresh girl, and look what you’ve done to me. I ought to call the police and tell them you raped me. Oh, you dirty, dirty old man.”
In March 1905 Demon Veen (in VN’s novel Ada, 1969, Van’s and Ada’s father) perishes in a mysterious airplane disaster above the Pacific. When Van and Ada (now married to Andrey Vinelander) meet in Mont Roux in October 1905, Ada mentions the hag who demanded certain fantastic sums which Demon had not had time to pay for "popping the hymen:"
‘My upper-lip space feels indecently naked.’ (He had shaved his mustache off with howls of pain in her presence). ‘And I cannot keep sucking in my belly all the time.’
According to Humbert Humbert (the narrator and main character in VN’s novel Lolita, 1955), he spent the period from September 1951 to June 1952 in Cantrip College, four hundred miles away from New York:
Describing Lucette's visit to Kingston (in VN’s novel Ada, 1969, Van's American University), Van Veen mentions the malheureux Pompier’s cheap novel La Condition Humaine:
Describing his first night with Lolita in The Enchanted Hunters (a hotel in Briceland), Humbert Humbert (the narrator and main character in VN's novel Lolita, 1955) mentions the hundreds of powdered bugs wheeling around the lamps in the soggy black night, full of ripple and stir:
In his Foreword and 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 a distinguished Zemblan scholar Oscar Nattochdag: