The scenes with Sarah (Riley Keough) in the swimming pool are almost exact recreations of scenes from Marilyn Monroe's last film, Something's Got to Give (1962), which was never completed due to her sudden unexpected death. The footage from that film can be found online.
When Sam watches his neighbours with binoculars, a cigarette and the phone in his hand, he is in the same position as Jeff in Rear Window (1954) by Hitchcock. Sam also has a Rear Window poster in his apartment.
The film takes place in 2011. The TV news segments shown in the film refer to the date.
Sam's ringtone is the theme from the Commodore 64 game, "The Last Ninja."
After the A24 credit, some slides pass by the screen: A Unicorn, a Tiger, a Snake and a Lion. UTSL = Under The Silver Lake.