The names of the characters (and even of their labs) were all taken from the novella The Turn of the Screw by Henry James.
The movie contains two references to Samuel Beckett's iconic play Waiting for Godot.
First when Jessie quotes the line, "They give birth astride of a grave, the light gleams an instant, then it's night once more."
The second reference is when Miles and Flora refer to themselves as Vladimir and Estragon, and to their father as Godot.
The familiarity that these young children display with Beckett's play, also serves as an additional clue that they, like Jessie, now exist only in Quint's mind.
Jessie, in a red dress, appears whenever Quint takes a red pill.
Similarly, by taking the blue pill, Quint is able to invoke Miles and Flora, who are later revealed to have been frozen all along, and are represented throughout by the color blue.
The red and blue pills were also intended to serve as a homage to The Matrix (1999).
The entire film was shot at a single location - An actual decommissioned chemical research and manufacturing facility spread over 30 acres in the city of Fitchburg in central Massachusetts.